Prof. Dr. Andreas Stöhr

ZHO / Optoelektronik
University of Duisburg-Essen

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Hub
  • 100 Gbit/s V-band Transmission Enabled by Coherent Radio-over-Fiber System with IF-OFDM Envelope Detection and SSBI Suppression
    Steeg, M. and Exner, F. and Tebart, J. and Czylwik, A. and Stohr, A.
    2020 33rd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2020 (2020)
    In this paper, the successful demonstration of a 100 Gbit/s wireless backhaul link in the V-band is reported for the first time. The proposed system has potential for real-world deployment since it exploits the contiguous unlicensed spectrum of 14 GHz in the 60 GHz V-band between 57 GHz and 71 GHz. Optical baseband modulation and free-running lasers for photonic up-conversion are employed in the wireless transmitter and simple Schottky-barrier diodes (SBD) for envelope detection are used in the wireless receiver. This combination makes perfect use of the scalability of photonic technology with respect to modulation bandwidth while being robust against phase-noise and frequency drifts at the same time. By utilizing a dual-polarization (DP) 16-QAM IF-OFDM signal no local oscillator is required at the wireless receiver. To achieve the required high spectral efficiency for 100 Gbit/s wireless transmission in the available spectrum as well as a low baseband bandwidth, signal-signal beat interference (SSBI) has been substantially reduced. This is attained by analyzing non-linearities in the wireless transmitter for identifying and setting the optimum power relation between the IF carrier and the OFDM signal. Experimentally, we report 100 Gbit/s wireless V-band transmission using a DP IF-OFDM 16-QAM modulation over 1 m distenace. The achieved overall BER before FEC and overall wireless spectral efficiency are 2.4.10^{-3}, and ∼ 7 bit/s/Hz, respectively. For simplicity, experiments were carried out in a laboratory environment. By using commercially available high-gain antennas and RF power amplifiers, the link budget could be increased by about 7080 dB which would lead to longer wireless distances in the range of several 100 meters up to kilometers. © 2020 URSI.
    view abstract10.23919/URSIGASS49373.2020.9232159
  • InP-based THz Beam Steering Leaky-Wave Antenna
    Lu, P. and Haddad, T. and Sievert, B. and Khani, B. and Makhlouf, S. and Dulme, S. and Fernandez Estevez, J. and Rennings, A. and Erni, D. and Pfeiffer, U.R. and Stohr, A.
    IEEE Transactions on Terahertz Science and Technology (2020)
    For mobile THz applications, integrated beam steering THz transmitters are essential. Beam steering approaches using leaky-wave antennas (LWAs) are quite attractive in that regard since they do not require complex feeding control circuits because beam steering is simply accomplished by sweeping the operating frequency. To date, only a few THz LWAs have been reported. These LWAs are based on polymer or graphene substrates and thus it is quite impossible to monolithically integrate these antennas with state-of-the-art indium phosphide (InP) based photonic or electronic THz sources and receivers. Therefore, in this paper, we report on an InP-based THz LWA for the first time. The developed and fabricated THz LWA consists of a periodic leaking microstrip line integrated with a grounded coplanar waveguide to microstrip line (GCPW-MSL) transition for future integration with InP-based photodiodes. For fabrication, a substrate-transfer process using silicon as carrier substrate for a 50 m thin InP THz antenna chip has been established. By changing the operating frequency from 230 GHz to 330 GHz, the fabricated antenna allows to sweep the beam direction quasi-linearly from -46 to 42, i.e. the total scanning angle is 88. The measured average realized gain and 3 dB beam width of a 1.5 mm wide InP LWA are ~11 dBi and 10. The paper furthermore discusses the use of the fabricated LWA for THz interconnects. CCBY
    view abstract10.1109/TTHZ.2020.3039460
  • OFDM joint communication-radar with leaky-wave antennas
    Steeg, M. and Exner, F. and Tebart, J. and Czylwik, A. and Stöhr, A.
    Electronics Letters 56 (2020)
    In this Letter, the authors report on a 26 GHz joint communication- radar system. By exploiting the beam steering features of leaky-wave antennas, angle-of-arrival estimation and multi-user transmission are achieved. Furthermore, the Zadoff-Chu preamble of the OFDM waveform is used to provide a frequency-modulated continuouswave radar signal. This way, the wide operational bandwidth is used for both, communications and radar, yielding high data throughput and precise user localisation. Experimentally, spectral-efficient 16-QAM multi-user 5 × 4 Gbit/s communications and user localisation with an accuracy of about 2 cm and ±1.5° is demonstrated. © 2020 The Institution of Engineering and Technology.
    view abstract10.1049/el.2020.1310
  • Ultra-low phase-noise photonic terahertz imaging system based on two-tone square-law detection
    Dülme, S. and Steeg, M. and Mohammad, I. and Schrinski, N. and Tebart, J. and Stöhr, A.
    Optics Express 28 (2020)
    In this paper, we demonstrate a phase-sensitive photonic terahertz imaging system, based on two-tone square-law detection with a record-low phase noise. The system comprises a high-frequency photodiode (PD) for THz generation and a square-law detector (SLD) for THz detection. Two terahertz of approximately 300 GHz tones, separated by an intermediate frequency (IF) (7 GHz-15 GHz), are generated in the PD by optical heterodyning and radiated into free-space. After transmission through a device-under-test, the two-tones are self-mixed inside the SLD. The mixing results in an IF-signal, which still contains the phase information of the terahertz tones. To achieve ultra-low phase-noise, we developed a new mixing scheme using a reference PD and a low-frequency electrical local oscillator (LO) to get rid of additional phase-noise terms. In combination with a second reference PD, the output signal of the SLD can be down-converted to the kHz region to realize lock-in detection with ultra-low phase noise. The evaluation of the phase-noise shows the to-date lowest reported value of phase deviation in a frequency domain photonic terahertz imaging and spectroscopy system of 0.034°. Consequently, we also attain a low minimum detectable path difference of 2 μm for a terahertz difference frequency of 15 GHz. This is in the same range as in coherent single-tone THz systems. At the same time, it lacks their complexity and restrictions caused by the necessary optical LOs, photoconductive antennas, temperature control and delay lines. © 2020 OSA - The Optical Society. All rights reserved.
    view abstract10.1364/OE.400405
  • 2D mm-Wave Beam Steering via Optical True-Time Delay and Leaky-Wave Antennas
    Steeg, M. and Lu, P. and Tebart, J. and Stohr, A.
    GeMiC 2019 - 2019 German Microwave Conference (2019)
    In this paper we outline a concept to provide 2-dimensional photonic-assisted beam steering at mm-wave frequencies by utilizing leaky-wave antennas and integrated optical beam forming networks. Thereby, heterodyne detection is employed to tune the RF for leaky-wave antenna (LWA) beam scanning by remotely changing the optical frequency of a tunable laser. Beam steering in the other dimension is provided via an optical true time delay (TTD) beam forming network, which is compatible to the LWA beam scanning even for multiple GHz of bandwidth. Through wavelength-division multiplexing and optical filters, multiple beams can be generated even at the same RF. To prove the concept a system based on discrete components is set up and used to demonstrate 2D beam steering of a 1 Gbit/s data signal in the 60 GHz band over 1.5 m wireless distance. © 2019 IMA - Institut fur Mikrowellen- und Antennentechnik e.V.
    view abstract10.23919/GEMIC.2019.8698162
  • 300 GHz Photonic Self-Mixing Imaging-System with vertical illuminated Triple-Transit-Region Photodiode Terahertz Emitters
    Dulme, S. and Lu, P. and Beling, A. and Stohr, A. and Grzeslo, M. and Morgan, J. and Steeg, M. and Lange, M. and Tebart, J. and Schrinski, N. and Mohammad, I. and Neerfeld, T.
    2019 IEEE International Topical Meeting on Microwave Photonics, MWP 2019 (2019)
    In this paper, we report a phase-sensitive photonic THz two-Tone self-mixing imaging system, comprising a self-developed vertical illuminated triple transit region photodiode (TTR-PD) and a commercial square law Schottky barrier diode as THz emitter and THz detector, respectively. Using the two-Tone self-mixing approach, the phase information of a device-under-Test can be extracted by down-mixing two THz signals inside the SBD, whereas the phase information remains in the output signal. The THz tones are generated by two free-running lasers and the TTR-PD, while one optical signal is externally modulated for double sideband carrier suppression. By means of the self-mixing, the phase noises of the free running lasers are canceled out. Using a second PD for the trigger, lock-in detection allows fast imaging speed, only limited by the integration constant. Beside the imaging system, we present the characteristics of the used vertically illuminated terahertz triple transit region photodiodes with thin depletion zone and small active areas. Numerical analysis by energy-balance model based TCAD simulations show transit-Time limitations over 200 GHz, due to the electron field management within the active photodiode layers and the resulting high electron velocities. Therefore, the fabricated TTR-PDs show a flat ± 2dB frequency response within the frequency range from 225 GHz to 305 GHz. By employing the proposed photonic two-Tone imaging system with the fabricated TTR-PDs, amplitude and phase difference vector images are taken at 299.5 GHz and 300.5 GHz. Metal and acrylic glass items inside a paper envelope are clearly visible, which demonstrates the potential of the system. © 2019 IEEE.
    view abstract10.1109/MWP.2019.8892098
  • 3D Radar Localization via Photonic Chirp Leaky-Wave Antenna Beam Scanning
    Steeg, M. and Tebart, J. and Neophytou, K. and Antoniades, M.A. and Iezekiel, S. and Stohr, A.
    2019 IEEE International Topical Meeting on Microwave Photonics, MWP 2019 (2019)
    We report a photonic frequency-modulated continuous wave (FMCW) radar system that provides 3D localization with a simple radar frontend. This is achieved by exploiting linearly polarized leaky-wave antennas (LWAs) for simultaneously scanning azimuth and elevation. As such, the FMCW frequency sweep is employed for radar operation as well as LWA beam steering for target angle estimation. The LWAs are based on series fed patches and provide beam steering from-20.7° to +18° in the frequency range of 24-33 GHz in the H-plane and a field of view from-18.9° to 33.3° in the E-plane. The FMCW signal is photonically generated from the wavelength chirp of a low-cost DFB laser. Coherent radio-over-fiber transport with photonic upconversion provides low loss distribution and frequency scaling. Finally, 3D radar localization is experimentally demonstrated by two orthogonal LWAs. A ranging accuracy of better than 4 cm and an angular accuracy of \approx 0.5{\circ} have been achieved without any dedicated radar post processing. © 2019 IEEE.
    view abstract10.1109/MWP.2019.8892214
  • Endfire transition from coplanar waveguide-to-WR3 rectangular waveguide for monolithic integration with THz photodiodes
    Makhlouf, S. and Khani, B. and Haddad, T. and Steeg, M. and Stöhr, A.
    2019 2nd International Workshop on Mobile Terahertz Systems, IWMTS 2019 (2019)
    In this paper, an endfire transition from coplanar-to-rectangular waveguide (CPW-to-WR3) for operation in the WR3-band (220-320 GHz) is presented. The transition is designed for providing connectivity between a monolithically integrated InP-based terahertz photodiode (PD) to a WR3 rectangular waveguide. The presented transition is based on a CPW-fed planar dipole antenna designed on InP substrate which placed in the E-plane of the rectangular waveguide. The dipole-based transition converts the direct coupled quasi-TEM CPW mode of the PD output to the TE10 mode of the rectangular waveguide. The proposed design provides a simple approach avoiding complex integration and packaging techniques like air bridges, ribbon-bonds, or via holes. Numerical analysis of the designed transition shows a wideband performance with a 3 dB insertion loss (IL) over 88 GHz bandwidth and a 10 dB return loss (RL) over 53 GHz bandwidth within the WR3-band. © 2019 IEEE
    view abstract10.1109/IWMTS.2019.8823686
  • Fully-Hermetic 71-86 GHz WR12 Coherent Photonic Mixer Providing an RF Output Power up to +15 dBm
    Khani, B. and Makhlouf, S. and Lackmann, J. and Steffan, A. and Honecker, J. and Stohr, A.
    GeMiC 2019 - 2019 German Microwave Conference (2019)
    Novel compact fully-hermetic E-band (71-86 GHz) coherent photonic mixer (CPX), featuring a rectangular waveguide WR12 output and providing an RF output power up to +15 dBm, is reported in this work. According to our knowledge, this is the highest reported output power level radiated directly from a photonic mixer module in the E-band frequency range. The fabricated WR12-CPX allows direct optical-to-wireless conversion of optical baseband or IF-band signals, e.g. for radio-over-fiber (RoF) fronthauling in mobile communications. The module comprises an InP-based balanced-PD (BPD) chip, a GaAs HEMT MMIC medium power amplifier, and a laminate-based grounded coplanar waveguide to rectangular waveguide (GCPW-WR12) transition. The transition couples the optically generated, e.g. via heterodyning, millimeter-wave signal from the output of the BPD chip to the WR12. It is based on a double-slot antenna structure and developed on a Rogers RT/duroid 5880 laminate with a thickness of 127 μm. The presented GCPW-WR12 transition enables the development of fully-hermetic photonic packages, which is required to improve the durability of the BPD chip. The transition design is optimized by utilizing a 3D electromagnetic simulation software for achieving a wide operational bandwidth with an average insertion loss (IL) of about 1.6 dB and a return loss (RL) higher than 15 dB in the frequency range of 71-86 GHz. Finally, the RF responsivity of the WR12-CPX module and the hermeticity of the transition are experimentally characterized. © 2019 IMA - Institut fur Mikrowellen- und Antennentechnik e.V.
    view abstract10.23919/GEMIC.2019.8698156
  • Multiuser 5G Hot-Spots Based on 60 GHz Leaky-Wave Antennas and WDM Radio-over-Fiber
    Steeg, M. and Szczęsny, M. and Stöhr, A.
    Lecture Notes in Electrical Engineering 555 (2019)
    This paper reports on photonic multiuser 5G hot-spots, that provide multiple beams by employing frequency steerable leaky-wave antennas. Therefore, a 60 GHz periodic leaky-wave antenna (LWA) has been developed, based on low loss substrate-integrated waveguide (SIW) technology, which is fabricated through standard PCB processes. The developed LWA operates in the V-band between 50 and 70 GHz and provides over 40° beam steering in the H-plane via frequency scanning. The capability for beam steering and multiple simultaneous beams from only one feeding port is combined with Radio-over-Fiber (RoF) techniques to provide a simple, compact and low-cost system for new applications in mm-wave communications. The proposed system enables centralized photonic beam steering in fiber-wireless transmission links, where up to 6 Gbit/s data rates are demonstrated using 64 QAM with IF-OFDM and simple receiver architectures. The multibeam capabilities provide a strong addition to RoF links by utilizing dense WDM channels to support multiple wireless users. Thereby, multiple low latency and high data rate wireless services can be provided via a single fiber-fed antenna. Finally, this concept is demonstrated by lab experiments, where three 1 Gbit/s OOK data signals were simultaneously transmitted and by a week-long field trial in a shopping mall, where two 1.5 Gbit/s real-time SDI video streams were transmitted. © 2019, Springer Nature Singapore Pte Ltd.
    view abstract10.1007/978-981-13-7086-1_16
  • Neuronlike impulses in a travelling wave structure loaded with resonant tunneling diodes and air bridges
    Essimbi, B.Z. and Stöhr, A. and Jäger, I. and Jäger, D.
    Journal of Physics Communications 3 (2019)
    In this paper a coplanar waveguide (CPW) periodically loaded with resonant tunneling diodes (RTDs) and air bridges (AB) is presented as a travelling wave (TW) structure for modelling the FitzHugh-Nagumo (FHN) equation and emulating the behaviour of the nerve axon. Based upon an electrical equivalent circuit, the principle of operation is discussed in the context of a lumped-element circuital model being compared to a distributed structure. The phenomena of wave formation and propagation are studied by computer experiments of the underlying nonlinear ordinary difference-differential equations (ODEs) and that of the approximated model nonlinear partial differential equations (PDEs). A key achievement is that this medium supports stable propagating shock waves (kinks and antikinks) when effects of AB are neglected as well as stable traveling pulses only determined by the parameters of the circuit. As a result, compact electronic circuits with features of real neural systems are developed to be an experimental medium mimicking neural activity and to be applied in ultra-fast signal processing. © 2019 The Author(s).
    view abstract10.1088/2399-6528/ab2661
  • Photonic integrated chips for millimeter-wave and THz beam steering antennas
    Lu, P. and Steeg, M. and Haddad, T. and Neophytou, K. and Makhlouf, S. and Dülme, S. and Grzeslo, M. and Rymanov, V. and Stöhr, A.
    International Conference on Transparent Optical Networks 2019-July (2019)
    This paper discusses the use of advantageous photonic integrated chips for beam switching antennas and beam steering antennas in the millimeter-wave and THz frequency ranges. Planar directive (up 15.4 dBi) frequency scanning leaky wave antennas (LWAs) connected to photodiodes for 5G beam steering (26 GHz and 60 GHz) with scanning angles up to 110° are reported. One and two dimensional (1D/2D) beam steering for wireless communication with multiple users as well as mobile terminal localization is demonstrated. Also, THz beam switching using lensed-assisted THz antenna arrays as well as THz beam steering using THz LWA and novel photonic integrated circuits (PICs) providing phase shift and true time delay (TTD) based optical beam forming networks are presented. © 2019 IEEE.
    view abstract10.1109/ICTON.2019.8840204
  • Polarization Diversity Photoreceiver Integration on 26 GHz PCB Leaky-Wave Antenna for Photonic Beam Steering Transmitter
    Steeg, M. and Dulme, S. and Tebart, J. and Neerfeld, T. and Rymanov, V. and Stohr, A.
    2019 IEEE International Topical Meeting on Microwave Photonics, MWP 2019 (2019)
    In this paper, we report on the integration of a photonic beam steering transmitter for the 5G26 GHz band. The transmitter, designed for fiber-To-The-Antenna applications, is based on an optical polarization diversity receiver and a PCB leaky-wave antenna. Therefore, an integrated photoreceiver with polarization dependent couplers and high frequency waveguide photodiodes provides optoelectronic conversion of an incoming radio-over-fiber (RoF) signal. The antenna is fabricated from low-cost PCB processes and includes a bias-Tee to provide an integration platform for the photodiode. The leaky-wave antenna further operates in the frequency range from 24 GHz to 33 GHz, where it scans its beam angle with changing the radio frequency. Thus, the integrated transmitter provides photonic beam steering via changing the beat frequency of the optical RoF signal due to the LWA frequency scanning behavior. A prototype transmitter has been successfully integrated, with which the photonic beam steering properties are experimentally demonstrated. © 2019 IEEE.
    view abstract10.1109/MWP.2019.8892168
  • Single Radio-Over-Fiber Link and RF Chain-Based 60 GHz Multi-Beam Transmission
    Habib, U. and Steeg, M. and Stohr, A. and Gomes, N.J.
    Journal of Lightwave Technology 37 (2019)
    An efficient multi-user transmission scheme at 60 GHz using a single-feed leaky wave antenna (LWA) and hence requiring only a single radio-over-fiber link and single RF chain is presented. A subcarrier multiplexed signal carrying different users' data is transported over 2.2 km of optical fiber and then upconverted to the 60 GHz band for transmission to multiple spatially separated users through the beam steering characteristics of the LWA. An overall sum data rate, the combined rate from all users, of 10.6 Gb/s using 16-QAM modulation serving ten users over a transmission bandwidth of 3.05 GHz or 20 users with QPSK over 6.1 GHz span, is achieved experimentally. The theoretical sum data rates for 6.1 GHz bandwidth for different numbers of users are calculated, considering the SNR degradation due to the angularly dispersed LWA beam, showing that data rates over 30 Gb/s can be obtained. Finally, a system design that improves coverage and spectrum efficiency through operating multiple LWAs with a single RF chain is demonstrated. © 1983-2012 IEEE.
    view abstract10.1109/JLT.2019.2896778
  • Via-Less Microstrip to Rectangular Waveguide Transition on InP
    Hussain, B. and Serafino, G. and Ghelfi, P. and Bogoni, A. and Stohr, A.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2019-September (2019)
    Indium-Phosphide (InP) is one of the most common materials used for realizing active devices working in the millimeter frequency range. The isotropic etching profile of InP substrates limits the realization of passive devices, thus requiring an expensive and lossy hybrid platform. This paper presents a via-less, cost-effective and efficient solution for InP substrate. By using the proposed planar solution, it is demonstrated that rectangular waveguides can be realized on InP by fabricating a bed of nails structure which acts as a reflecting boundary for an impinging millimeter wave. As a proof of concept, a transition from microstrip to rectangular waveguide structure is realized within H-band (220-320 GHz) with a return loss of-18dB over a bandwidth of 30 GHz. © 2019 IEEE.
    view abstract10.1109/IRMMW-THz.2019.8874316
  • All Photonic Radar System based on Laser Frequency Sweeping and Leaky-Wave Antennas
    Steeg, M. and Al Assad, A. and Stöhr, A.
    MWP 2018 - 2018 International Topical Meeting on Microwave Photonics (2018)
    In this paper, we report on a novel all photonic FMCW radar system for detection and localization of multiple objects. This is achieved by utilizing the self-sweeping functionality of tunable external cavity lasers (ECL) in combination with optical heterodyning for generating a millimeter-wave FMCW radar signal. In order to also localize the objects, frequency scanning mm-wave leaky-wave antennas (LWAs) are used. The LWAs enable beam steering via the FMCW signal for estimating the direction of arrival (DoA) of the radar echos. Overall, this approach yields very compact all photonic radar systems that do not require electrical oscillators or optical modulators. In addition, thanks to the LWAs, multiple objects can be localized within a single sweep and without any clock or control signals. Experimentally, the performance of a developed all photonic 60 GHz radar with a 10 GHz bandwidth is demonstrated for multiple object detection and localization. It is shown that the developed radar provides a range and DoA angle estimation error of <1 cm and ∼3°, respectively. This is achieved without using any dedicated radar signal post-processing algorithms. © 2018 IEEE.
    view abstract10.1109/MWP.2018.8552839
  • Compact Optoelectronic THz Frequency Domain Spectroscopy System for Refractive Index Determination based on Fabry-Perot Effect
    Dülme, S. and Schrinski, N. and Khani, B. and Lu, P. and Rymanov, V. and Stöhr, A. and Brenner, C. and Hofmann, M.R.
    2018 1st International Workshop on Mobile Terahertz Systems, IWMTS 2018 (2018)
    In this work, we present a compact optoelectronic THz frequency domain spectroscopy (FDS) system for determination the real part of the refractive index of a semiconductor wafer with a given thickness. The concept is based on the detection of transmission maxima, which appear due to Fabry-Perot interferences inside the wafer and which depend on the refractive index of the semiconductor material. This all-fiber based THz FDS setup consists of two external cavity laser diodes and an uni-traveling-carrier photodiode (UTC-PD) module on the emitter side, while a Schottky barrier diode (SBD) is used as THz receiver. Since we don't need any additional lenses and because of the small device dimensions, this setup is compact in size, compared with traditional bulky TDS systems. We prove our THz FDS concept by characterizing of a semi-insulating iron-doped indium phosphide (InP:Fe) wafers with different thicknesses within a frequency range from 220 GHz up to 450 GHz. Based on the determination of the free spectral range (FSR) between the Fabry-Perot transmission maxima, a refractive index of 3.475 for this frequency region is obtained. Additional THz time domain spectroscopy experiments match the THz FDS results very well and confirm our results. Furthermore, analytic calculations are in excellent agreement with the measurements. A planned transfer of this THz FDS approach to a completely hybrid or monolithic integration of all photonic devices in a compact module could be offer a very small and full mobile THz spectroscopy setup. © 2018 IEEE.
    view abstract10.1109/IWMTS.2018.8454695
  • Continuous Wave Multimode Amplitude THz Spectroscopy
    Gerling, A. and Dulme, S. and Schrinski, N. and Stohr, A. and Hofmann, M.R. and Brenner, C.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2018-September (2018)
    THz spectroscopy with continuous wave lasers is typically based on the frequency tuning of the lasers. This process is rather slow, and some systems require additional sophisticated postprocessing. We propose a multimode system without postprocessing requirements to reduce measurement time. For this, we use a modulation scheme with multiple laser sources to enable snapshot amplitude THz spectroscopy. As the detection is performed with a Schottky barrier diode the scheme is very fast but discards phase information. This approach makes amplitude THz spectroscopy possible without frequency tuning or any moving mechanical parts. © 2018 IEEE.
    view abstract10.1109/IRMMW-THz.2018.8510486
  • Design of PCB leaky-wave antennas for Wide angle beam steering
    Neophytou, K. and Iezekiel, S. and Steeg, M. and Stöhr, A.
    GeMiC 2018 - 2018 German Microwave Conference 2018-January (2018)
    A PCB based leaky-wave antenna (LWA) design for wide angle beam steering is presented. This design employs longitudinal slots inserted into a substrate-integrated waveguide for operation in the mm-wave V-band. It is optimized for a reduced open-stopband and linear through broadside beam steering. The base design is outlined and adapted for three high frequency laminates with different dielectric constants. It is further described how the dielectric constant directly affects the beam steering properties of the LWA and how to scale the achieved beam angle for the given design by only changing the PCB material. The three LWA designs achieve beam steering from about 45° at ϵr =2.2, over 60° at ϵr =6.15 to 75° at ϵr =10.2. The simulated radiation patterns show a flat gain of up to 18.0 dBi, 17.85 dBi and 15.27 dBi respectively. Furthermore, the effect of the modified PCB permittivity on the radiation efficiency as well as multiuser support with a beam per user is investigated. © 2018 IMA.
    view abstract10.23919/GEMIC.2018.8335052
  • Estimating direction-of-arrival in a 5G hot-spot scenario using a 60 GHz leaky-wave antenna
    Husain, B. and Steeg, M. and Stohr, A.
    2017 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems, COMCAS 2017 2017-November (2018)
    A novel direction of arrival (DoA) estimation system based on a PCB substrate-integrated waveguide (SIW) leaky-wave antenna (LWA) is presented. The antenna provides high broadside efficiency and low return loss in the frequency range of operation from 50 to 70 GHz. The antenna consists of an array of SIW fed microstrip antennas and can be fabricated through cost-effective PCB processes. The proposed scheme only requires a low-cost passive LWA antenna and is thus much more cost and power efficient when compared to the traditional DoA estimation techniques based on phased array antennas, which also require a high processing gain. One power detector is utilized to estimate the DoA by measuring the received power at the LWA port. This technique has a coverage range of +/- 8 degrees and can be employed to estimate received signal DoA of a mobile user which is up to 1 m away from the receiver. An experimental measurement for the proposed DoA estimation technique is presented along with the LWA radiation pattern. © 2017 IEEE.
    view abstract10.1109/COMCAS.2017.8244845
  • InP-Based Grounded Coplanar Waveguide to WR3 Transition for Monolithic Integration with THz Photodiodes
    Khani, B. and Makhlouf, S. and Diilme, S. and Stohr, A.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2018-September (2018)
    A novel monolithic integration concept of an indium phosphide (InP) THz-photodiode (PD) featuring a rectangular waveguide output is presented. The concept is based on a planar grounded coplanar waveguide to rectangular waveguide (GCPW-to-WR3) transition designed on an InP substrate. The presented integration eliminates the need for complex and high-cost hybrid integration and packaging techniques, like flip-chip, wire-bonding, and split-block. The numerical analysis of the designed transition shows a 3dB bandwidth of 44 GHz within the WR3-band. Its electrical performance and bandwidth are compared with the ultra-thin low-dielectric liquid crystalline polymer-based GCPW-to-WR3 transition. © 2018 IEEE.
    view abstract10.1109/IRMMW-THz.2018.8509914
  • Low-latency GbE 60 GHz TDD transceiver using SiGe-RFICs and PCB leaky-wave antennas
    Steeg, M. and Lange, M. and Stöhr, A. and Leiba, Y.
    GeMiC 2018 - 2018 German Microwave Conference 2018-January (2018)
    In this work, a low-cost and low-latency 60 GHz transceiver supporting beam steering in 5G hot-spots is presented. Beam steering is achieved via carrier frequency tuning by using a voltage-controlled oscillator (VCO) and a PCB based leaky-wave antenna (LWA). Besides enabling inherent beam steering, which does not add to the link latency, the LWA also requires only one RF port even for multiple beams. The fabricated LWA provides up to 20 dBi directivity within the 50-70 GHz band. Within this bandwidth, over 40 deg beam steering is achieved. The employed SiGe 60 GHz transceiver RFIC is highly integrated. It includes RF and baseband amplifier chains, mixers, filters and the VCO with a control loop. The transceiver RFIC is fabricated using a BiCMOS foundry process providing scalability and low-cost. By integrating the SiGe RFIC with the LWA, a Gigabit-Ethernet (GbE) wireless transceiver is developed providing time division duplex (TDD) 60 GHz wireless communication with a standardized GbE interface. The 60 GHz transceivers are employed in a 2 m long wireless communication link, which is experimentally evaluated using an IP traffic tester. A latency of about 0.4 ms and an aggregated data rate of almost 1 Gbit/s is experimentally achieved. © 2018 IMA.
    view abstract10.23919/GEMIC.2018.8335053
  • Metallic 3D Printed Rectangular Waveguides (WR3) for Rapid Prototyping of THz Packages
    Makhlouf, S. and Khani, B. and Lackmann, J. and Dulme, S. and Stöhr, A.
    2018 1st International Workshop on Mobile Terahertz Systems, IWMTS 2018 (2018)
    In this work, laser beam melting (LBM) is used for direct 3D printing of hollow-metallic rectangular waveguides (WRs) within the WR3-band (230-320 GHz). By using laser beam melting of stainless steel (SS) 316L powder, a WR3 waveguide is fabricated in a single 3D printing process. This eliminates the need for costly mechanical and chemical post-printing processes required in traditional micromachining and non-metallic 3D printing technologies. In addition, the metallic LBM waveguides outperform the non-metallic ones in mechanical robustness. On the other hand, the surface roughness for LBM SS316L is typically higher as compared to non-metallic printed structures. For rectangular waveguides, this leads to slightly higher transmission losses. According to these performances, 3D metallic printing can be considered as a suitable technology for rapid prototyping, e.g. for high-frequency photodiode (PD) packages, where complex PD packages are printed in a single fabrication step. Since the length of the rectangular waveguide in the terahertz photodiode package is only a few millimeter long, slightly higher transmission losses can be accommodated. To investigate the use of LBM technology for THz PD packages, the impact of the surface roughness on the electrical performance of the fabricated waveguides is numerically and experimentally analyzed. The measured average inner surface roughness is about 50 μm, whereas it is about 47.7 μm at the WR3 flange surface, resulting in an RF insertion loss of about 0.7 dB/mm. By smoothing the WR3 flange surface to values as low as 2 μm via a simple milling process, RF losses are reduced down to 0.3 dB/mm. © 2018 IEEE.
    view abstract10.1109/IWMTS.2018.8454684
  • Near Infrared Diode Laser THz Systems
    Brenner, C. and Hu, Y. and Gwaro, J. and Surkamp, N. and Döpke, B. and Hofmann, M.R. and Kani, B. and Stöhr, A. and Sumpf, B. and Klehr, A. and Fricke, J.
    Advances in Radio Science 16 (2018)
    The generation and detection of radiation in the THz frequency range can be achieved with many different electronic and photonic concepts. Among the many different photonic THz systems the most versatile are based on diode lasers. In this paper we describe and review the different concepts and optimization ideas for diode laser based THz systems in order to achieve the best performance for different types of THz setups. © Author(s) 2018.
    view abstract10.5194/ars-16-167-2018
  • Phase Delay of Terahertz Fabry-Perot Resonator characterized by a Photonic Two-Tone Spectroscopy System with Self-Heterodyne Receiver
    Dulme, S. and Schrinski, N. and Steeg, M. and Lu, P. and Khani, B. and Brenner, C. and Hofmann, M.R. and Stohr, A.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2018-September (2018)
    Terahertz phase delay of high-resistive Silicon based Fabry-Perot resonators (FPR) is experimentally investigated using a photonic two-tone THz spectroscopy system with a self-heterodyne receiver. The photonic spectroscopy system consists of two free-running lasers of which one is externally modulated and an InP-based photodiode for two-tone THz signal generation. A Schottky barrier diode (SBD) is employed as self-heterodyne THz receiver. This way, spectroscopic THz phase and amplitude characterization is enabled without bulky delay lines and the phase noise of the two free running lasers is canceled out. By employing the developed photonic spectroscopy system, phase delay and transmission of a THz FPR is experimentally characterized between 270 GHz and 305 GHz. It is furthermore shown, that the measured THz phase delay difference and FSR of 23 degrees and 13 GHz, respectively, as well as the measured THz transmission coefficient agree well with an analytic model for the phase delay of a Fabry-Perot resonator. © 2018 IEEE.
    view abstract10.1109/IRMMW-THz.2018.8510021
  • Photonic assisted beam steering for millimeter-wave and THz antennas
    Lu, P. and Steeg, M. and Kolpatzeck, K. and Dulme, S. and Khani, B. and Czylwik, A. and Stohr, A.
    2018 IEEE Conference on Antenna Measurements and Applications, CAMA 2018 (2018)
    This manuscript discusses photonic assisted beam steering and beam switching millimeter-wave and THz antennas. Planar frequency scanning 60 GHz band leaky wave antennas (LWA) providing up to 15.4 dBi gain and scanning angles up to 110° are reported next to 300 GHz band LWAs with a max. directivity of 16 dBi and 72° scanning angle. Furthermore, photonic beam forming networks (OBFN) for true time delay (TTD) and phased array wideband (275-350 GHz) THz antennas are described. Finally, multiple beam antenna arrays for 1D and 2D beam switching are shown. Experimentally, 1D THz beam switching of 18° is demonstrated. Simulation results for 2D beam switching show a scanning angle of 70°. © 2018 IEEE.
    view abstract10.1109/CAMA.2018.8530567
  • Planar 0.05-1.1 THz Laminate-Based Transition Designs for Integrating High-Frequency Photodiodes with Rectangular Waveguides
    Khani, B. and Makhlouf, S. and Steffan, A. and Honecker, J. and Stohr, A.
    Journal of Lightwave Technology (2018)
    Compact planar laminate-based transitions for integrating high-frequency photodiodes (PDs) with rectangular waveguides (WRs) are presented for the WR15 to WR1 standard waveguide bands, i.e. from 0.05 THz up to 1.1 THz. The transitions couple the optically generated (e.g. via heterodyning) millimeter-wave or terahertz signals from the grounded coplanar waveguide (GCPW) output of the PD chip to the WR. To our knowledge, this is the first scalable integration concept that enables hermetic photodiode packaging up to the terahertz frequency range. For the WR15-WR6 bands, all transitions are designed on ultra-thin microfiber reinforced PTFE composites (127 &#x03BC;m Rogers RT/duroid 5880 laminate). For the WR5-WR2.2 and the WR1.5-WR1 bands, liquid crystalline polymer ULTRALAM 3850 laminates are used with a thickness of 50 &#x03BC;m and 25 &#x03BC;m, respectively. The proposed GCPW-WR transition design is based on a double-slot antenna structure and enables the development of fully-hermetic photonic packages, which is required to improve the durability of the PD chip. The transition designs are optimized by systematic EM-wave propagation modelling for achieving a wide operational bandwidth of up to 30% of the respective center frequency for each WR band. The optimized transitions exhibit an average insertion loss (IL) of about 1.5 dB and a return loss (RL) of about 10 dB for all waveguide bands (WR15-WR1). Based upon the systematic numerical modeling, generic guidelines are developed that allow designing a specific transition for any given waveguide band to 1.1 THz. In addition to the numerical analysis, GCPW-WR12 transitions for E-band (60-90 GHz) operation are fabricated and integrated with InP-based balanced-PD (BPD) chips and GaAs HEMT MMIC medium power amplifiers in a fully-hermetic package. Furthermore, hermetic WR12 coherent photonic mixer (CPX) modules are developed. The packaged WR12-type CPX allows direct optical-to-wireless conversion of optical baseband or IF-band signals e.g. for radio-over-fiber (RoF) fronthauling in mobile communications. The WR12-CPX modules provide RF output power of up to +15 dBm at 77.5 GHz. OAPA
    view abstract10.1109/JLT.2018.2885647
  • Public field trial of a Multi-RAT (60 GHz 5G/ LTE/WiFi) mobile network
    Steeg, M. and Gomes, N.J. and Juarez, A.A. and Kosciesza, M. and Lange, M. and Leiba, Y. and Mano, H. and Murata, H. and Szczesny, M. and Stohr, A.
    IEEE Wireless Communications 25 (2018)
    A public field trial showcasing an operational RAT mobile network was implemented in one of the largest shopping malls in Warsaw, Poland. The network supports novel 60 GHz 5G mobile access as well as legacy LTE and WiFi services All mobile access services of the network are interconnected via optical fiber to the data centers of a mobile network operator and an Internet service provider. Fronthauling for the 60 GHz 5G hotspot Rau and for LTE is realized by analog RoF via a fiber optic DAS. The 60 GHz 5G Raus for the eMBB use case and the WiFi AP are both backhauled via optical Gigabit Ethernet. The 60 GHz Raus for the eMBB and hotspot use case feature 2D beam-switching and 1D beam-steering, respectively. Inter-RAT switching between the different mobile services with seamless user experience is achieved using a Mobile IP system with FILS. © 2002-2012 IEEE.
    view abstract10.1109/MWC.2018.1800052
  • Radio-over-Fiber-supported Millimeter-wave Multiuser Transmission with Low-Complexity Antenna Units
    Habib, U. and Steeg, M. and Stöhr, A. and Gomes, N.J.
    MWP 2018 - 2018 International Topical Meeting on Microwave Photonics (2018)
    A system for serving a large number of users at millimeter-wave (mmW) frequencies using a single Radio Frequency (RF) chain is presented. A single Remote Antenna Unit (RAU) supported by Radio-over-Fiber transport is used to transmit multiple 60GHz band signals to various users located at different spatial locations using the beamsteering characteristics of a Leaky Wave Antenna (LWA). Error Vector Magnitude analysis has been performed for each user signal up to a maximum of seven users per RF chain with wireless transmission over 2m. A performance comparison for different user-signal frequency spacings has been provided to understand the limitations of the system and results show that the proposed system design with the LWA performs better than systems using waveguide and horn antenna transmitters. A realization to double the number of served users is also presented which shows that up to 10 users can be served using half region of the LWA, with each user transmitting 1Gb/s data rate, delivering an aggregate data rate of 10Gb/s. © 2018 IEEE.
    view abstract10.1109/MWP.2018.8552904
  • Simultaneous DoA Estimation and Ranging of Multiple Objects using an FMCW Radar with 60 GHz Leaky-Wave Antennas
    Steeg, M. and Assad, A.A. and Stohr, A.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2018-September (2018)
    In this paper an FMCW radar system for simultaneous distance and direction estimation of multiple objects with a single sweep is reported. Therefore, a frequency scanning leaky-wave antenna (LWA), providing 60°beam steering from 50 to 60 GHz and over 110°within the V-band, is utilized. The radar is operated to cover the full section within a single frequency sweep. Thus, fast radar operation is enabled, and the distance and direction of multiple objects is obtained from the time dependent spectral components of the received IF signal. © 2018 IEEE.
    view abstract10.1109/IRMMW-THz.2018.8510169
  • Terahertz near field coupling for integrating III-V photodiodes on silicon
    Dülme, S. and Khani, B. and Rymanov, V. and Lu, P. and Stöhr, A.
    GeMiC 2018 - 2018 German Microwave Conference 2018-January (2018)
    A novel compact terahertz near field coupling (NFC) based hybrid integration platform for interconnecting active III-V semiconductor devices, e.g. a high frequency photodiode (PD), on Silicon is designed, simulated, and fabricated. The studied NFC approach allows mounting InP-based triple transit region photodiodes (TTR-PD) with integrated log periodic toothed antenna (LPTA) as Terahertz transmitter on a highly resistive silicon (HR-Si) substrate receiving the terahertz radiation via a second LPTA. The electrical THz output power of the TTR-PD is transferred using electromagnetic NFC to the receiving antenna. Numerical simulations of the NFC integration technique show an insertion loss (IL) of 2 dB at 250 GHz with a return loss (RL) better than 10 dB. A 3dB operating bandwidth of 43 GHz (234 GHz-277 GHz) is achieved. © 2018 IMA.
    view abstract10.23919/GEMIC.2018.8335083
  • Coherent Radio-over-Fiber THz communication link for high data-rate 59 Gbit/s 64-QAM-OFDM and real-time HDTV transmission
    Stöhr, A. and Hermelo, M.F. and Steeg, M. and Boris Shih, P.-T. and Ng'oma, A.
    Optics InfoBase Conference Papers Part F40-OFC 2017 (2017)
    We report a coherent Radio-over-Fiber (CRoF) THz communication link supporting both, off-line high data-rate 59 Gbit/s transmission using a record spectral efficient 64-QAMOFDM modulation as well as real-time HDTV transmission at 328 GHz carrier frequency. © 2017 OSA.
    view abstract10.1364/OFC.2017.Tu3B.2
  • Field trial of a hybrid fiber wireless (HFW) bridge for 2.5 Gbit/s GPON
    Chuenchom, R. and Banach, A. and Leiba, Y. and Lech, M. and Schrinski, N. and Yaghoubiannia, M. and Steffan, A. and Honecker, J. and Stohr, A.
    International Conference on Transparent Optical Networks (2017)
    In this paper, we report on a field trial, demonstrating the seamless wireless extension of a real-world 2.5 Gbit/s Gigabit passive optical network (GPON) using a hybrid fiber wireless (HFW) bridge. Direct optic-to-RF conversion using a novel coherent photonic mixer (CPX) and direct RF-to-optic radio access units (RAU) were developed and employed to extend the reach of the GPON network using a 455 m long-distance 73.5 GHz millimeter-wave point-to-point (PTP) wireless link. The wireless GPON bridge was synchronized to the downlink transmission line rate of 2.5 Gbit/s. In the field trial, as total downlink traffic of about 2.5 Gbit/s was transmitted over SMF and the wireless bridge between the OLT and three ONU. The total uplink traffic from two ONUs to the OLT was about 1.2 Gbit/s. © 2017 IEEE.
    view abstract10.1109/ICTON.2017.8025157
  • High data rate 6 Gbit/s steerable multibeam 60 GHz antennas for 5G hot-spot use cases
    Steeg, M. and Stöhr, A.
    Summer Topicals Meeting Series, SUM 2017 (2017)
    We present a steerable 60 GHz band multibeam antenna for high-capacity 5G hot-spot-scenarios. The developed SIW-LWA-antenna provides about 40° beam steering and a 14 dBi H-plane directivity. Wireless transmission to multiple users and maximum user data rates up to 6 Gbit/s are demonstrated. © 2017 IEEE.
    view abstract10.1109/PHOSST.2017.8012690
  • Photonic-Assisted mm-Wave and THz Wireless Transmission towards 100 Gbit/s Data Rate
    Hermelo, M.F. and Chuenchom, R. and Rymanov, V. and Kaiser, T. and Sheikh, F. and Czylwik, A. and Stöhr, A.
    Frequenz 71 (2017)
    This paper presents photonic-assisted 60 GHz mm-wave and 325 GHz system approaches that enable the transmission of spectral-efficient and high data rate signals over fiber and over air. First, we focus on generic channel characteristics within the mm-wave 60 GHz band and at the terahertz (THz) band around 325 GHz. Next, for generating the high data rate baseband signals, we present a technical solution for constructing an extreme bandwidth arbitrary waveform generator (AWG). We then report the development of a novel coherent photonic mixer (CPX) module for direct optic-to-RF conversion of extreme wideband optical signals, with a >5 dB higher conversion gain compared to conventional photodiodes. Finally, we experimentally demonstrate record spectral efficient wireless transmission for both bands. The achieved spectral efficiencies reach 10 bit/s/Hz for the 60 GHz band and 6 bit/s/Hz for the 325 GHz band. The maximum data rate transmitted at THz frequencies in the 325 GHz band is 59 Gbit/s using a 64-QAM-OFDM modulation format and a 10 GHz wide data signal. © 2017 Walter de Gruyter GmbH, Berlin/Boston.
    view abstract10.1515/freq-2017-0147
  • Plasmonic photodetector with THz electrical bandwidth
    Mousavi, S.S. and Berini, P. and Stöhr, A.
    2017 Photonics North, PN 2017 (2017)
    A plasmonic photodetector based on nanomonopoles is proposed and investigated. The detection region is a thin film of InGaAs, placed on a n-doped InP substrate. The responsivity of the photodetector is estimated to be ∼200 mA/W, while its 3 dB electrical bandwidth is ∼ 1 THz. © 2017 IEEE.
    view abstract10.1109/PN.2017.8090568
  • Spectral efficient 64-QAM-OFDM terahertz communication link
    Hermelo, M.F. and Shih, P.-T. and Steeg, M. and Ng'oma, A. and Stöhr, A.
    Optics Express 25 (2017)
    We report on a record spectral efficient terahertz communication system using a coherent radio-over-fiber (CRoF) approach. High spectral efficient back-to-back and wireless THz transmission around 325 GHz is experimentally demonstrated using a 64-QAM-OFDM modulation format and a 10 GHz wide wireless channel resulting in a data rate of 59 Gbit/s. © 2017 Optical Society of America.
    view abstract10.1364/OE.25.019360
  • Substrate-integratedwaveguide PCB leaky-wave antenna design providing multiple steerable beams in the V-band
    Steeg, M. and Yonemoto, N. and Tebart, J. and Stöhr, A.
    Electronics (Switzerland) 6 (2017)
    A periodic leaky-wave antenna (LWA) design based on low loss substrate-integrated waveguide (SIW) technologywith inset half-wavemicrostrip antennas is presented. The developed LWA operates in the V-band between 50 and 70 GHz and has been fabricated using standard printed circuit board (PCB) technology. The presented LWA is highly functional and very compact supporting 1D beam steering and multibeam operation with only a single radio frequency (RF) feeding port. Within the operational 50–70 GHz bandwidth, the LWA scans through broadside, providing over 40° H-plane beam steering. When operated within the 57–66 GHz band, the maximum steering angle is 18.2°. The maximum gain of the fabricated LWAs is 15.4 dBi with only a small gain variation of +/–1.5 dB across the operational bandwidth. The beam steering and multibeam capability of the fabricated LWA is further utilized to support mobile users in a 60 GHz hot-spot. For a single user, a maximum wireless on-off keying (OOK) data rate of 2.5 Gbit/s is demonstrated. Multibeam operation is achieved using the LWA in combination with multiple dense wavelength division multiplexing (WDM) channels and remote optical heterodyning. Experimentally, multibeam operation supporting three users within a 57–66 GHz hot-spot with a total wireless cell capacity of 3 Gbit/s is achieved. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.
    view abstract10.3390/electronics6040107
  • The 2017 terahertz science and technology roadmap
    Dhillon, S.S. and Vitiello, M.S. and Linfield, E.H. and Davies, A.G. and Hoffmann, M.C. and Booske, J. and Paoloni, C. and Gensch, M. and Weightman, P. and Williams, G.P. and Castro-Camus, E. and Cumming, D.R.S. and Simoens, F. and Escorcia-Carranza, I. and Grant, J. and Lucyszyn, S. and Kuwata-Gonokami, M. and Konishi, K. and Koch, M. and Schmuttenmaer, C.A. and Cocker, T.L. and Huber, R. and Markelz, A.G. and Taylor, Z.D. and Wallace, V.P. and Axel Zeitler, J. and Sibik, J. and Korter, T.M. and Ellison, B. and Rea, S. and Goldsmith, P. and Cooper, K.B. and Appleby, R. and Pardo, D. and Huggard, P.G. and Krozer, V. and Shams, H. and Fice, M. and Renaud, C. and Seeds, A. and Stöhr, A. and Naftaly, M. and Ridler, N. and Clarke, R. and Cunningham, J.E. and Johnston, M.B.
    Journal of Physics D: Applied Physics 50 (2017)
    Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz-30 THz) have developed rapidly over the last 30 years. For most of the 20th Century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to 'real world' applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2017, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 18 sections that cover most of the key areas of THz science and technology. We hope that The 2017 Roadmap on THz science and technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies. © 2017 IOP Publishing Ltd.
    view abstract10.1088/1361-6463/50/4/043001
  • Coherent photonic 70 GHz band mixer module with WR-12 output
    Khani, B. and Rymanov, V. and Honecker, J. and Steeg, M. and Steffan, A.G. and Stöhr, A.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2016-November (2016)
    In this work, we present a novel compact rectangular-waveguide-type (WR-12) coherent photonic mixer module, featuring a balanced photodetector. The module enables the direct fiber-to-the-antenna connectivity for the upcoming 5G links. Experimental results with respect to the output RF power (e.g., -7.3 dBm at 73 GHz) and the frequency response deviation (±0.5 dB) are presented within the 71-76 GHz range. © 2016 IEEE.
    view abstract10.1109/IRMMW-THz.2016.7758666
  • Compact rectangular-waveguide (WR-12) transition for coherent photonic mixers
    Khani, B. and Rymanov, V. and Honecker, J. and Steffan, A.G. and Stöhr, A.
    2016 Global Symposium on Millimeter Waves, GSMM 2016 and ESA Workshop on Millimetre-Wave Technology and Applications (2016)
    A compact E-band (71-76 GHz) conductor-backed coplanar waveguide (CBCPW) to hollow metallic waveguide (WR-12) transition has been designed and fabricated. The fully-planar two-layer transition makes use of a double-slot antenna, which efficiently couples the millimeter-wave (mm-wave) signal from the CBCPW to the WR-12 waveguide. The introduced transition, together with an integrated high-speed balanced photodetector (BPD), enables the development of a compact coherent photonic mixer featuring a WR-12 output (WR12-CPX). The mm-wave generation is realized by heterodyne coherent optical detection in the BPD chip. The WR12-CPX allows direct optical-to-wireless conversion, enabling fiber-to-the-antenna connectivity for mobile backhauling. The transition is designed and fabricated on a 127 μm thick ROGERS RT/duroid 5880 laminate (ϵr = 2.2). The experimental results of the fabricated transition show a maximum insertion loss of 3 dB and an average return loss of ∼20 dB. In addition to that, the packaged transition is presented as part of a novel WR12-CPX module. © 2016 IEEE.
    view abstract10.1109/GSMM.2016.7500287
  • E-Band 76-GHz coherent RoF backhaul link using an integrated photonic mixer
    Chuenchom, R. and Zou, X. and Schrinski, N. and Babiel, S. and Freire Hermelo, M. and Steeg, M. and Steffan, A. and Honecker, J. and Leiba, Y. and Stöhr, A.
    Journal of Lightwave Technology 34 (2016)
    An E-band 76-GHz coherent radio-over-fiber (CRoF) system has been developed employing an integrated coherent photonic mixer (CPX) in the radio access unit (Rau) and a Schottky envelope detector in the wireless receiver. The CPX basically consists of a 2 × 2 multi-mode interferometer (MMI) coupled to a balanced photodiode (PD). It enables direct conversion of the optical baseband signal to the wireless RF signal with a carrier frequency at 76 GHz using a local oscillator located in the Rau. The developed CPX module features a V-type connector. The 3-dB cut-off frequency and 1-dB saturation output power of the CPX module are estimated as ∼70 GHz and -2.43 dBm, respectively. It is shown that due to the integration of the MMI and the balanced PD, the developed CPX outperforms a commercial 110-GHz PD in terms of conversion efficiency up to 92 GHz. Experimentally, long-distance wireless transmission is shown using the constructed CRoF system and highly directive antennas with a gain of 43 dBi each. A wireless transmission of 1 Gb/s non-return-to-zero data signal at 76 GHz carrier frequency is demonstrated up to 230 m. The receiver sensitivity of the constructed wireless receiver for a pre-FEC bit error rate of 10-3 has been measured to be -34.8 dBm. This has enabled wireless data transmission over 92 m and 230 m at transmit power levels as low as -11.17 dBm and -3.36 dBm, respectively. It is shown that the experimental transmit power levels agree well with the expected figures calculated using an analytic Friis model describing the wireless channel. It is also estimated that the system could support maximum wireless distances up to 2000 m. © 1983-2012 IEEE.
    view abstract10.1109/JLT.2016.2573047
  • Highly spectral-efficient and high capacity millimeter-wave wireless data transmission using a Coherent Radio-over-Fiber system (CRoF)
    Stöhr, A. and Hermelo, M.F. and Chuenchom, R. and Rymanov, V. and Khani, B. and Zou, X. and Honecker, J. and Steffan, A.G.
    2016 21st European Conference on Networks and Optical Communications, NOC 2016 (2016)
    This paper reports on the development of a packaged coherent photonic mixer (CPX) for coherent Radio-over-Fiber (RoF) systems. The developed integrated CPX performs direct optical-to-RF up-conversion with a 5 dB better conversion efficiency at 60 GHz as compared to a commercially available 110 GHz photodiode. The 3 dB bandwidth and maximum RF output power of the CPX are 65 GHz and +7 dBm, respectively. By utilizing the developed CPX module in a CRoF system, we demonstrate 1 Gbit/s NRZ data transmission over 25 km long fiber and a 230 m long wireless link within the 71-76 GHz band. Furthermore, a novel IF-CRoF architecture is presented enabling high-capacity 21 Gbit/s wireless 60 GHz transmission using a 64 QAM-OFDM modulation format and record spectral-efficiency (9 bit/s/Hz) wireless transmission using a 512 QAM-OFDM modulation. © 2016 IEEE.
    view abstract10.1109/NOC.2016.7507013
  • Novel 50-70 GHz compact PCB leaky-wave antenna with high broadside efficiency and low return loss
    Steeg, M. and Khani, B. and Rymanov, V. and Stöhr, A.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2016-November (2016)
    Here, we propose a novel leaky-wave antenna operating in the V-band. The antenna provides high broadside efficiency and low return loss in the frequency range of operation from 50 to 70 GHz. The antenna consists of an array of substrate integrated waveguide fed dipoles and can be fabricated through cost-effective PCB processes. High peak directivities of over 20 dBi are obtained for a compact (4 × 80 mm2) array consisting of only 20 unit cells. The directivity is flat (+/-1 dB deviation) and can be further increased by enlarging the array. Furthermore the antenna provides over 40 deg of beam steering in the frequency range of operation. © 2016 IEEE.
    view abstract10.1109/IRMMW-THz.2016.7758489
  • Photonics for microwave measurements
    Zou, X. and Lu, B. and Pan, W. and Yan, L. and Stöhr, A. and Yao, J.
    Laser and Photonics Reviews 10 (2016)
    As an emerging topic, photonic-assisted microwave measurements with distinct features such as wide frequency coverage, large instantaneous bandwidth, low frequency-dependent loss, and immunity to electromagnetic interference, have been extensively studied recently. In this article, we provide a comprehensive overview of the latest advances in photonic microwave measurements, including microwave spectrum analysis, instantaneous frequency measurement, microwave channelization, Doppler frequency-shift measurement, angle-of-arrival detection, time–frequency analysis, compressive sensing, and phase-noise measurement. A photonic microwave radar, as a functional measurement system, is also reviewed. The performance of the photonic measurement solutions is evaluated and compared with the electronic solutions. Future prospects using photonic integrated circuits and software-defined architectures to further improve the measurement performance are also discussed. (Figure presented.). © 2016 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
    view abstract10.1002/lpor.201600019
  • Planar E-Band (71-76 GHz) Platforms for Integrating Millimeter Wave Photodiodes with WR-12 Waveguides
    Khani, B. and Rymanov, V. and Dülme, S. and Flammia, I. and Stöhr, A.
    Periodica Polytechnica, Electrical Engineering 60 (2016)
    A planar 71-76 GHz integration platform is designed and fabricated for high-power radio-over-fiber (RoF) wireless photonic transmitters (PTs). The platform enables the integration of high-electron-mobility-transistor RF amplifiers and millimeter wave photodiodes (PDs), e.g., the waveguide triple transit region PD. An efficient electrical coupling between the PD chip and the rectangular waveguide (WR-12) output is attained through a low-loss grounded coplanar waveguide to a rectangular waveguide transition. The integration platform features a novel planar bias-tee design making use of a single quarter-wave coupled-lines (SCLs) section and slotted splitring resonators (SRRs). The bias-tee network enables proper biasing for the PD chip and protects the hybrid integrated RF amplifier from being damaged by the DC bias voltage. The introduced design together with the WR-12 output enables the development of high-power (>17 dBm) PTs for mobile backhaul links and radar applications. Experimental characterization of the designed platform is introduced and compared to numerical results.
    view abstract10.3311/PPee.8908
  • Ultrafast surface plasmon III-V photodetectors based on nanomonopoles
    Mousavi, S.S. and Stöhr, A. and Berini, P.
    Journal of Lightwave Technology 34 (2016)
    A nanoantenna-based plasmonic photodetector is proposed and investigated theoretically. An array of interconnected nanomonopoles on a film of InGaAs on n-doped InP is modeled. The infrared (∼1550 nm) responsivity of the structure can reach ∼200 mA/W for a 20-nm-thick InGaAs layer. The optimum 3-dB electrical bandwidth of the device is calculated to be ∼1 THz for the case of a 20-nm-thick InGaAs layer and a 4 × 4 nanomonopole array. The electrical bandwidth is shown to increase by decreasing the number of elements in the array. A simple linear model for the total resistance of the structure is proposed and validated. The total resistance increases by increasing the thickness of the InGaAs layer and by decreasing the number of array elements. © 1983-2012 IEEE.
    view abstract10.1109/JLT.2016.2575002
  • 10 GHz channel spacing ultra-dense WDM networks transparently extended by mm-wave coherent RoF links
    Steeg, M. and Babiel, S. and Chuenchom, R. and Stöhr, A.
    2015 IEEE International Conference on Communication Workshop, ICCW 2015 (2015)
    The extension of ultra-dense WDM passive optical networks (PONs) by millimetre-wave coherent radio-over-fiber (RoF) links is investigated. For a seamless and transparent integration of the RoF links coherent heterodyne detection is used for the generation of the wireless RF signals out of the optical baseband data signals. Simulations of the optical SIR in the PON are carried out in dependence on the WDM channel spacing. The projected impact on the transmission quality is derived and WDM CRoF experiments are performed. In the experiments three data modulated optical channels are transmitted over 10 km SMF to simulate the PON, before arriving at the E-band radio access unit (RAU). The RAU utilizes heterodyne detection with an optical LO for converting the 1 Gb/s optical baseband signal to a 75 GHz RF signal. After 40 m wireless transmission the signal is received by an antenna and downconverted to baseband using a low-cost SBD based receiver for envelope detection. The filtering of WDM channels with an optical channel spacing of down to 10 GHz showed very little penalty versus single channel transmission, relying only on the filter characteristic of the used LNAs and antennas and using no optical filters. Still the receiver's sensitivity is only -57 dBm for a bit error rate (BER) of 2·10-3, thus it is shown that an ultra-dense WDM PON can be extended wirelessly using coherent RoF techniques without the need for optical filtering. © 2015 IEEE.
    view abstract10.1109/ICCW.2015.7247199
  • Compact E-Band (71-86 GHz) bias-tee module for external biasing of millimeter wave photodiodes
    Khani, B. and Rymanov, V. and Steeg, M. and Buck, A. and Dülme, S. and Stöhr, A.
    2015 International Topical Meeting on Microwave Photonics, MWP 2015 - Conference Proceedings (2015)
    This paper focuses on the development and characterization of a novel E-band planar bias-tee (BT) circuit featuring a high-speed millimeter wave photodiode (mm-wave PD) module to be integrated in next generation access and mobile networks (5G). The designed bias-tee circuit together with the integrated mm-wave PD chip, i.e., triple transit region photodiode (TTR-PD) allows the development of high-power Radio-over-Fiber (RoF) E-band (70/80 GHz) photonic transmitters (PTs) to be used in wireless extension and mobile backhaul links. The introduced BT circuit provides the protection to the hybrid integrated RF amplifier from being damaged by the PD bias voltage and prevents the leakage of the RF signal through the DC path. The vector network analyzer (VNA) measurements of the BT circuit show that in the frequency range from 70 to 75 GHz, the return loss (RL) is higher than 11 dB, the RF signal suppression level (IS) in the DC path is higher than 30 dB, while the insertion loss (IL) is lower than 2 dB. For optical RF signal generation, two laser sources are used to generate an optical heterodyne signal. Lower dark current levels and a 3-dB bandwidth in the frequency range from 71 to 86 GHz have been demonstrated at the BT output. © 2015 IEEE.
    view abstract10.1109/MWP.2015.7356673
  • Compact triple transit region photodiode module with WR-12 rectangular waveguide output
    Rymanov, V. and Khani, B. and Dulme, S. and Steeg, M. and Stöhr, A.
    2015 International Topical Meeting on Microwave Photonics, MWP 2015 - Conference Proceedings (2015)
    Here, we present a compact photonic transmitter module featuring an integrated InP-based 1.55 μm triple transit region photodiode (TTR-PD) chip and a WR-12 rectangular waveguide output for E-band (60-90 GHz) radio-over-fiber applications. In order to enable work capability in broadband wireless E-band communications over long- and medium-range distances, the fabricated TTR-PD module provides excellent frequency flatness exhibiting a maximum deviation of ±1 dB within the complete 71-86 GHz band and high-power levels in excess of -5 dBm (without external amplification) at a photocurrent of 10 mA. In addition, we report for the first time on non-isothermal analyses of TTR-PDs using the drift-diffusion model with integrated Joule heat generation. © 2015 IEEE.
    view abstract10.1109/MWP.2015.7356701
  • Integrated 110 GHz coherent photonic mixer for CRoF mobile backhaul links
    Chuenchom, R. and Zou, X. and Rymanov, V. and Khani, B. and Steeg, M. and Dulme, S. and Babiel, S. and Stöhr, A. and Honecker, J. and Steffan, A.G.
    2015 International Topical Meeting on Microwave Photonics, MWP 2015 - Conference Proceedings (2015)
    An integrated 110 GHz coherent photonic mixer (CPX) is designed and fabricated for coherent RoF (CRoF) mobile backhaul links. The CPX simultaneously performs optical WDM channel selection and direct optical-to-RF conversion. Due to its broadband performance, the CPX simultaneously supports future wireless systems operating in the 57-64 GHz, 71-76 GHz, 81-86 GHz bands and even research-type W-band systems. The RF frequency response of the CPX in the 60 GHz and 70/80 GHz bands is about 4 dB higher as compared to a commercial 110 GHz photodiode. A CRoF experiment is carried out to also prove the advantageous performance of the new 110 GHz CPX against a commercially available 110 GHz photodiode in a CRoF system experiment with a 25 km standard single-mode fiber (SMF) and a 40 m long 71-76 GHz wireless link. This experiment reveals a significant improvement in optical receiver sensitivity of the radio access unit (Rau) with a required optical signal power as low as -32 dBm at a BER=2×10-3 for a 1 Gbit/s NRZ-OOK data signal. © 2015 IEEE.
    view abstract10.1109/MWP.2015.7356699
  • Passive Ψ-type optical polarization splitter for integrated photonic polarization diversity receivers
    Rymanov, V. and Khani, B. and Dulme, S. and Enkisch, K. and Krause, A. and Stöhr, A.
    European Conference on Optical Communication, ECOC 2015-November (2015)
    Here, we report on a completely passive InGaAsP/InP-based Ψ-type optical polarization splitter (as part of an integrated 1.55 μm photonic polarization diversity receiver), which exhibits splitting ratios up to 14.1 dB and 22.3 dB for TE- and TM-polarized light, respectively. © 2015 Viajes el Corte Ingles, VECISA.
    view abstract10.1109/ECOC.2015.7341737
  • Planar 71-76 GHz laminate integration platform for connecting millimeter wave photodiodes to WR-12 waveguides
    Khani, B. and Rymanov, V. and Flammia, I. and Stöhr, A.
    International Conference on Transparent Optical Networks 2015-August (2015)
    Here, a millimeter wave photodiode (mm-wave PD) integration platform for development of high-power Radio-over-Fiber (RoF) wireless photonic transmitters (PTs) is presented. The platform features a novel planar bias-tee network design making use of a single quarter-wave coupled-line (CL) technique and two slotted split-ring resonators (SRRs) integrated in the DC bias line. The introduced bias-tee network enables proper biasing for mm-wave PDs, e.g. the triple transit region photodiode (TTR-PD), and protects the hybrid integrated RF amplifier from being damaged by the bias voltage. The 3D full-wave electromagnetic field simulations of the designed bias-tee network show that in the whole 71-76 GHz band, the return loss (RL) is higher than 20 dB, the RF signal suppression level (IS) is higher than 30 dB, while the insertion loss (IL) is lower than 0.6 dB. A fence of via holes surrounds the bias-tee network to reduce the RF propagation losses into the laminate and to ensure that the grounded coplanar waveguide (GCPW) supports only a quasi-static transverse electromagnetic mode (TEM). The bias-tee network integrated together with high-electron-mobility transistor (HEMT) RF amplifiers and GCPW-to-rectangular waveguide (WR) transition enables the development of high-power (>17 dBm) PTs with WR-12 output. The IL of the complete integration platform is ∼2.2 dB. © 2015 IEEE.
    view abstract10.1109/ICTON.2015.7193499
  • Planar bias-tee circuit using single coupled-line approach for 71-76 GHz photonic transmitters
    Khani, B. and Rymanov, V. and Flammia, I. and Miech, M. and Stöhr, A.
    2015 German Microwave Conference, GeMiC 2015 (2015)
    This paper presents a novel planar bias-tee (BT) circuit comprising a quarter-wave single coupled-line (SCL) section designed on 127 μm thick ROGERS RT/duroid 5880 laminate for E-band (71-76 GHz) wireless photonic transmitters. The BT circuit enables proper biasing for millimeter wave photodiodes (mm-wave PDs) through the RF-choke, and in addition, protects the hybrid integrated RF amplifier from being damaged by the DC voltage using the SCL DC-block. The planar RF-chock design is based upon two slotted split-ring resonators (SRRs) and is integrated in the DC bias line in order to prevent the leak of the RF signal into the voltage circuitry. Numerical results of the DC-block section show that in the entire 71-76 GHz band, the return loss (RL) is higher than 36 dB while the insertion loss (IL) is lower than 0.4 dB. The overall performance of the complete BT circuit (DC-block and RF-choke) has been calculated by the 3D full-wave electromagnetic field simulator based on the finite element method (RL > 20 dB, IL < 0.6 dB and RF signal suppression in the DC bias line (IS) > 30 dB). A via hole fencing surrounds the BT circuit to reduce the RF propagation losses into the laminate and to ensure that the grounded coplanar waveguide (GCPW) supports only a quasi-static TEM mode. © 2015 IMA: IMATech e.V.
    view abstract10.1109/GEMIC.2015.7107807
  • 60 GHz grounded-coplanar-waveguide-tosubstrate-integrated-waveguide transition for RoF transmitters
    Flammia, I. and Khani, B. and Arafat, S. and Stöhr, A.
    Electronics Letters 50 (2014)
    A novel transition from a grounded-coplanar waveguide to a substrate integrated-waveguide (SIW) is presented featuring a fully planar bias tee for the development of 60 GHz radio-over-fibre photonic transmitters for indoor applications. The transition is intended to serve as a connection between a 60 GHz photodiode chip and SIW antennas suitable for indoor data distribution. Simulations show that in the whole 57-64 GHz communication band, the return loss (RL) is at least 15 dB, whereas the insertion loss (IL), is < 0.9 dB. Measurements of a back-to-back configuration confirm the numerical results, with a IL of ~2 dB and a RL > 12 dB. © The Institution of Engineering and Technology 2014.
    view abstract10.1049/el.2013.3533
  • Coherent radio-over-fiber (CRoF) approach for heterogeneous wireless-optical networks
    Babiel, S. and Chuenchom, R. and Stöhr, A. and Mitchell, J.E. and Leiba, Y.
    2014 International Topical Meeting on Microwave Photonics / the 9th Asia-Pacific Microwave Photonics Conference, MWP/APMP 2014 - Proceedings (2014)
    A new coherent optical heterodyne radio-over-fiber (CRoF) scheme is proposed for seamless integration of next generation millimeter-wave wireless systems into a (ultra-dense) next generation passive optical network (NG-PON2). For seamless integration with the (ultra-dense) WDM infrastructure of high-capacity and longer-reach NG-PON2 networks, we propose novel radio access units (RAU) using coherent optical heterodyne detection for the generation of the millimeter-wave radio signals. The proposed CRoF concept supports the provision of multiple services over a single optical distribution network including next generation optical and wireless access services and high-capacity fixed wireless links for mobile backhaul. A proof-of-concept experiment is demonstrated in the context of backhauling. An E-band RAU utilizing CRoF is used for converting 2.5 Gb/s optical baseband data after 20 km fiber transmission to a 76 GHz wireless signal. After subsequent wireless transmission over 40 m (limited by the lab environment), the wireless E-band signal is directly reconverted to 2.5 Gb/s baseband data using a low-cost 76 GHz wireless receiver with RF envelope detection. The receiver's sensitivity is only -47 dBm for a bit error rate (BER) of 2.10-3. Within international regulations, the transmit RF power can be further increased by about 68 dB, i.e. wireless distances way beyond 2 km can be expected even in the case of rain. © 2014 IEICE.
    view abstract10.1109/MWP.2014.6994480
  • Dual-frequency laser phase locked at 100 GHz
    Pillet, G. and Morvan, L. and Ménager, L. and Garcia, A. and Babiel, S. and Stöhr, A.
    Journal of Lightwave Technology 32 (2014)
    We report on the generation of low phase noise millimeter-wave signal at 100 GHz with a dual-frequency laser and a high-speed photodiode. The laser beatnote is phase-locked on the tenth harmonic of a 10 GHz synthesizer through a new photonic down-converter based on a phase modulator. The spectral purity of the millimeter-wave signal has been fully characterized: it is spurious free over a large bandwidth and its phase noise is limited by the synthesizer itself (-90 dBc/Hz at 10 kHz). © 2012 IEEE.
    view abstract10.1109/JLT.2014.2333036
  • DWDM-PON/mm-Wave wireless converged next generation access topology using coherent heterodyne detection
    Thakur, M.P. and Mikroulis, S. and Renaud, C.C. and Mitchell, J.E. and Stöhr, A.
    International Conference on Transparent Optical Networks (2014)
    A radio-over-fibre system using coherent optical heterodyne detection scheme is proposed, to achieve seamless integration of a photonic Remote Antenna Unit (RAU) into a Next Generation Dense Wavelength Division Multiplexed Passive Optical Network (NG DWDM-PON). The proposed scheme significantly simplifies the optical mm-wave generation and data recovery as it doesn't require any high-bandwidth modulator at the central office or high-frequency Local Oscillators (LOs) at either the central office or the customer unit; or optical phase-locking techniques to generate the mm-wave wireless signal. A proof-of-concept transmission utilizing 1 Gb/s On-Off Keying is experimentally demonstrated. © 2014 IEEE.
    view abstract10.1109/ICTON.2014.6876454
  • Plasmonic photodetector with terahertz electrical bandwidth
    Mousavi, S.S. and Stöhr, A. and Berini, P.
    Applied Physics Letters 104 (2014)
    We propose and investigate a surface plasmon photodetector concept, based on the enhancement of electrical near-field in low-defect, low-doped In 0.53Ga0.47As detection volumes located in the gaps of an array of metal nanodipole antennas. We report enhancement in responsivity in the presence of nanodipoles and predict a maximum responsivity of ∼100 mA/W at wavelengths near 1550 nm. The 3 dB electrical bandwidth of the device is estimated based on its RC rise time and the hole transit time through the detection volume for the cases of conventional and ballistic transport in InGaAs and is found to range from ∼0.7 to 4 THz. Also, trends are observed relating the responsivity to the gap dimensions, revealing a trade-off between the field-enhancement in the gap and its volume, and leading to an optimum gap length producing the maximum responsivity. © 2014 AIP Publishing LLC.
    view abstract10.1063/1.4870974
  • Robust 71-76 GHz radio-over-fiber wireless link with high-dynamic range photonic assisted transmitter and laser phase-noise insensitive SBD receiver
    Stöhr, A. and Cojucari, O. and Van Dijk, F. and Carpintero, G. and Tekin, T. and Formont, S. and Flammia, I. and Rymanov, V. and Khani, B. and Chuenchom, R.
    Conference on Optical Fiber Communication, Technical Digest Series (2014)
    This paper describes a robust radio-over-fiber wireless link system for use in wireless extension and mobile backhaul applications. The wireless link operates at 71-75 GHz E-band carrier frequencies and can transmit ultra-high access data such as Gigabit Ethernet or OC-48 up to 2.5 Gbps. Enabling photonic technologies, system configurations, and lab trials are presented. © 2014 OSA.
    view abstract10.1109/OFC.2014.6886531
  • Surface plasmon nanoantenna-based photodetector with Terahertz electrical bandwidth
    Mousavi, S.S. and Berini, P. and Stöhr, A.
    2014 International Topical Meeting on Microwave Photonics / the 9th Asia-Pacific Microwave Photonics Conference, MWP/APMP 2014 - Proceedings (2014)
    A surface plasmon nanoantenna-based photo-detector is proposed and investigated. An array of nanodipoles on an InP substrate is assumed, where the detection region consists of volumes of InGaAs located in the gaps of the nanodipoles. The responsivity of the photodetector is estimated to be ∼100 mA/W at its peak value. A trend is observed for the power absorption in the detection region as a function of gap size; an optimum gap size exists that maximizes the product of the gap volume and the electric field enhancement in the gap. The 3 dB electrical bandwidth of the device is calculated assuming conventional and ballistic carrier transit in the detection region, yielding 0.7-4 THz. © 2014 IEICE.
    view abstract10.1109/MWP.2014.6994590
  • Transparent wireless access to optical WDM networks using a novel coherent radio-over-fiber (CRoF) approach
    Stöhr, A. and Mitchell, J.E. and Leiba, Y.
    International Conference on Transparent Optical Networks (2014)
    A new coherent optical heterodyne radio-over-fiber (CRoF) scheme is presented for the transparent integration of millimeter-wave wireless systems into next generation optical WDM networks. For seamless integration with the (ultra-dense) WDM infrastructure of high-capacity and longer-reach optical access networks, we propose novel radio access units (RAU) based upon a coherent optical heterodyne detection approach. The proposed CRoF concept supports the provision of multiple services over a single optical distribution network including next generation optical and wireless access services and high-capacity fixed wireless links for mobile backhaul. Proof-of-concept experiments for transparent integration of 60 GHz wireless access systems and 70/80 GHz wireless backhauling links will be presented. © 2014 IEEE.
    view abstract10.1109/ICTON.2014.6876615
  • Triple transit region photodiodes (TTR-PDs) providing high millimeter wave output power
    Rymanov, V. and Stöhr, A. and Dülme, S. and Tekin, T.
    Optics Express 22 (2014)
    We report on a novel triple transit region (TTR) layer structure for 1.55 μm waveguide photodiodes (PDs) providing high output power in the millimeter wave (mmW) regime. Basically, the TTR-PD layer structure consists of three transit layers, in which electrons drift at saturation velocity or even at overshoot velocity. Sufficiently strong electric fields (&gt;3000 V/cm) are achieved in all three transit layers even in the undepleted absorber layer and even at very high optical input power levels. This is achieved by incorporating three 10 nm thick p-doped electric field clamp layers. Numerical simulations using the drift-diffusion model (DDM) indicate that for optical intensities up to ∼500 kW/cm2, no saturation effects occur, i.e. the electric field exceeds the critical electric field in all three transit layers. This fact in conjunction with a high-frequency doublemushroom cross-section of the waveguide TTR-PD ensures high output power levels at mmW frequencies. Fabricated 1.55 μm InGaAs(P)/InP waveguide TTR-PDs exhibit output power levels exceeding 0 dBm (1 mW) and a return loss (RL) up to ∼24 dB. Broadband operation with a 3 dB bandwidth beyond 110 GHz is achieved. © 2014 Optical Society of America.
    view abstract10.1364/OE.22.007550
  • A novel transition from grounded coplanar waveguide to substrate inte grated waveguide for 60 GHz Radio-over-Fiber photonic transmitters
    Flammia, I. and Khani, B. and Stöhr, A.
    Proceedings of 13th Conference on Microwave Techniques, COMITE 2013 - MAREW 2013: Microwave and Radio Electronics Week 2013 (2013)
    We present a novel transition from grounded coplanar waveguide (GCPW) to substrate integrated waveguide (SIW), designed on a ROGERS 5880 laminate for 60 GHz Radio-over-Fiber (RoF) photonic transmitters. The transition serves as connection between a 60 GHz photodiode (PD) chip and a suitable SIW antenna. In contrast to previous designs, our approach makes use of a quarter-wave coupled-lines (CL) section to transfer the signal carried by the GCPW to the SIW. This technique, creating a DC-block between the GCPW signal track and the ground layers, allows for correctly biasing the PD. In order to reduce the propagation of parasitic modes as well as the risk of interferences, the transition is fully enclosed by a fence of via holes. Simulations show that in the whole 57-64 GHz band, the return loss (RL) is higher than 17 dB, while the insertion loss (IL) is &Sim; 0.4 dB. To prevent the loss of RF power through the DC path, a planar RF-choke (RL > 22 dB, IL < 0.4 dB and RF-to-DC isolation (IS) higher than 28 dB) is additionally integrated. © 2013 IEEE.
    view abstract10.1109/COMITE.2013.6545046
  • Compact modules for wireless communication systems in the E-band (71-76 GHz)
    Montero-De-Paz, J. and Oprea, I. and Rymanov, V. and Babiel, S. and García-Muñoz, L.E. and Lisauskas, A. and Hoefle, M. and Jimenez, A. and Cojocari, O. and Segovia-Vargas, D. and Palandöken, M. and Tekin, T. and Stöhr, A. and Carpintero, G.
    Journal of Infrared, Millimeter, and Terahertz Waves 34 (2013)
    The millimeter-wave spectrum above 70 GHz provides a cost-effective solution to increase the wireless communications data rates by increasing the carrier wave frequencies. We report on the development of two key components of a wireless transmission system, a high-speed photodiode (HS-PD) and a Schottky Barrier Diode (SBD). Both components operate uncooled, a key issue in the development of compact modules. On the transmitter side, an improved design of the HS-PD allows it to deliver an output RF power exceeding 0 dBm (1 mW). On the receiver side, we present the design process and achieved results on the development of a compact direct envelope detection receiver based on a quasi-optical SDB module. Different resonant (meander dipole) and broadband (Log-Spiral and Log-Periodic) planar antenna solutions are designed, matching the antenna and Schottky diode impedances at high frequency. Impedance matching at baseband is also provided by means of an impedance transition to a 50 Ohm output. From this comparison, we demonstrate the excellent performance of the broadband antennas over the entire E-band by setting up a short-range wireless link transmitting a 1 Gbps data signal. © 2013 Springer Science+Business Media New York.
    view abstract10.1007/s10762-013-9967-5
  • E-band (71-76 GHz) wireless link using compact modules
    Montero-De-Paz, J. and Oprea, I. and Rymanov, V. and Babiel, S. and García-Muñoz, L.E. and Lisauskas, A. and Hoefle, M. and Jimenez, A. and Cojocari, O. and Segovia-Vargas, D. and Stöhr, A. and Carpintero, G.
    Electronics Letters 49 (2013)
    Wireless links using carrier waves in the millimetre-wave spectrum above 70 GHz provide a cost-effective solution to increase the data rate. Reported is the development of a photonically enabled link, based on two compact modules, both operated uncooled, transmitting a 1 Gbit/s data signal over several metres. The first module includes an optimised high-speed photodiode, delivering an output RF power exceeding 0 dBm (1 mW). Also reported is the development of a direct envelope receiver based on a quasi-optical Schottky barrier diode (SBD) module. Over the carrier frequency range, the broadband log-periodic antenna impedance has been optimised to match the SBD, while at the baseband frequency, the receiver was optimised to a 50 O output through an impedance transition. These have been key issues for the excellent performance of the compact receiver module over the entire E-band. © The Institution of Engineering and Technology 2013.
    view abstract10.1049/el.2012.4301
  • Novel quasi-hermetic photodiode module featuring an E-band rectangular waveguide (WR-12) output
    Flammia, I. and Babiel, S. and Leonhardt, C.C. and Honecker, J. and Steffan, A.G. and Stöhr, A.
    IEEE Photonics Technology Letters 25 (2013)
    A quasi-hermetic photodiode module featuring a WR-12 rectangular waveguide (RW) output has been developed for operation in the E-band. The module makes use of a grounded coplanar-waveguide-to-rectangular-waveguide transition implemented on a Rogers RT/duroid 5880 laminate that does not require any mechanical modifications of the RW. Simulations show that the transition has excellent radio frequency (RF) characteristics (return loss larger than 30 dB, insertion loss smaller than 2 dB, maximum group delay deviation smaller than 1 ps). Measurements confirm the simulated results and highlight the importance of via-holes to reduce the overall loss. The maximum output power delivered by the module, at a DC photocurrent of 10 mA, is rm -12.5 dBm. At 73 GHz, the 1-dB compression point is found to be at a photocurrent of ∼ 9 mA, with an RF output power of ∼ -13.5 dBm. The measured output power has less than 1 dB ripple in the frequency range of interest. © 1989-2012 IEEE.
    view abstract10.1109/LPT.2012.2234096
  • Radio-over-fiber photonic wireless bridge in the W-Band
    Babiel, S. and Stöhr, A. and Kanno, A. and Kawanishi, T.
    2013 IEEE International Conference on Communications Workshops, ICC 2013 (2013)
    In this paper, we present a photonic wireless system operating in the W-Band (75-110 GHz) featuring ultra-high bandwidth as well as simple NRZ-OOK modulation format. By using a cascaded optical RF and data modulation approach on the transmitter side, flexible adjustment of the wireless RF carrier in the W-Band is achieved, while direct electrical to optical conversion with advanced photonic components on the receiver side enables true photonic wireless bridging. In first experiments, data rates up to 10 Gb/s have been experimentally demonstrated. © 2013 IEEE.
    view abstract10.1109/ICCW.2013.6649350
  • Substrate integrated waveguide antenna for 60 GHz radio-over-fiber transmitter
    Flammia, I. and Khani, B. and Stöhr, A.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz (2013)
    We present a substrate integrated waveguide (SIW) antenna designed for 60 GHz indoor Radio-over-Fiber photonic transmitters. For broad-band applications (57-64 GHz) a return loss (RL) higher than 7 dB and a front-to-back ratio (FTBR) of 17 dB are achieved. Alternative resonant solutions are also introduced to achieve RL > 10 dB and FTBR = 21 dB. © 2013 IEEE.
    view abstract10.1109/IRMMW-THz.2013.6665594
  • Ultra-broadband integrated photonic 200-300 GHz transmitters for wireless radio-over-fiber applications
    Rymanov, V. and Babiel, S. and Wachholz, M. and Dülme, S. and Stöhr, A.
    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz (2013)
    Here, we report on planar photonic transmitters employing high-speed 1.55 μm photodiodes. Within the 200-300 GHz band, the device exhibits a 6-dB bandwidth along with a polarization penalty of ∼2.2 dB. Besides, the chip area is reduced thanks to a novel integration approach in the antenna structure. © 2013 IEEE.
    view abstract10.1109/IRMMW-THz.2013.6665453
  • 100 GHz phase-locked dual-frequency laser
    Pillet, G. and Morvan, L. and Menager, L. and Garcia, A. and Babiel, S. and Stöhr, A.
    2012 IEEE International Topical Meeting on Microwave Photonics, MWP 2012 - Proceedings (2012)
    We report on the generation of a low phase noise millimeter-wave signal at 100 GHz with a dual-frequency laser and a high-speed photodiode. The laser beatnote is phase-locked on the 10th harmonics of a 10 GHz synthesizer through an original photonic down-conversion scheme. The spectral purity of the millimeter wave signal has been fully characterized: it is spurious free over a large bandwidth and its phase noise is limited by the synthesizer itself (-90 dBc/Hz at 10 kHz). © 2012 IEEE.
    view abstract10.1109/MWP.2012.6474048
  • 71-76GHz grounded CPW to WR-12 transition for quasi-hermetic RoF wireless transmitter
    Flammia, I. and Stöhr, A. and Leonhardt, C.C. and Honecker, J. and Steffan, A.G.
    Electronics Letters 48 (2012)
    A grounded coplanar waveguide (GCPW) to rectangular waveguide (WR) transition is presented for operation in the E-band from 71 to 76GHz, a worldwide allocated frequency slot for wireless communication. The GCPW-to-WR transition is designated for the E-band radio-over-fibre (RoF) wireless transmitter where it connects the 50 Ω coplanar waveguide (CPW) output of a high-frequency photodiode chip to a WR-12 waveguide. The presented transition is implemented on a ROGERS RT/Duroid 5880 RF laminate, it allows for quasi-hermetic packaging without the need of radomes and enables the use of a commercially available WR without the need for any mechanical modifications. Full-wave electromagnetic simulations show that the optimised transition presents a return loss of at least 30dB and an insertion loss (IL) of only 2dB. Experimental results confirm an average IL of only 2.5dB. The key role of via-holes in reducing the IL is experimentally proven. © 2012 The Institution of Engineering and Technology.
    view abstract10.1049/el.2012.0377
  • Double mushroom 1.55-μm waveguide photodetectors for integrated E-band (60-90 GHz) wireless transmitter modules
    Rymanov, V. and Tekin, T. and Stöhr, A.
    Proceedings of SPIE - The International Society for Optical Engineering 8259 (2012)
    High data rate photonic wireless systems operating at millimeter wave carrier frequencies are considered as a disruptive technology e.g. for reach extension in optical access networks and for mobile backhauling. Recently, we demonstrated 60 GHz photonic wireless systems with record data rates up to 27 Gbit/s. Because of the oxygen absorption at 60 GHz, it is beneficial for fixed wireless systems with spans exceeding 1 km to operate at even higher frequencies. Here, the recently regulated 10 GHz bandwidth within the E-band (60-90 GHz) is of particular interest, covering the 71-76 GHz and 81-86 GHz allocations for multi-gigabit wireless transmission. For this purpose, wideband waveguide photodetectors with high external quantum efficiency are required. Here, we report on double mushroom 1.55 μm waveguide photodetectors for integration in an E-band wireless transmitter module. The developed photodetector consists of a partially p-doped, partly non-intentionally doped absorbing layer centered in a mushroom-type optical waveguide, overcoming the compromise between the junction capacitance and the series resistance. For efficient fiber-chip coupling, a second mushroom-type passive optical waveguide is used. In contrast to the conventional shallow ridge waveguide approach, the mushroom-type passive waveguide allows to shift the center of the optical mode further away from the top surface, thus reducing waveguide losses due to the surface roughness. Experimentally, a very flat frequency response with a deviation up to ±1 dB in the entire E-band has been found together with an output power level of -15.7 dBm at 10 mA photocurrent and at a frequency of 73 GHz. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
    view abstract10.1117/12.908767
  • Integrated photonic 71-76 GHz transmitter module employing high linearity double mushroom-type 1.55 μm waveguide photodiodes
    Rymanov, V. and Palandoken, M. and Lutzmann, S. and Bouhlal, B. and Tekin, T. and Stöhr, A.
    2012 IEEE International Topical Meeting on Microwave Photonics, MWP 2012 - Proceedings (2012)
    Here, we present novel high-power partially p-doped, partly non-intentionally doped absorbing double mushroom-type 1.55 μm waveguide photodiodes for integration in compact photonic transmitter modules employed in E-band (60-90 GHz) radio-over-fiber systems. Besides the high-output power levels approaching 0 dBm and a high linearity in the 70 GHz band, the developed photodiodes also exhibit an excellent frequency flatness and a return loss of ±0.5 dB and ∼24 dB, respectively. For low-cost packaging, the photodiodes are hybrid integrated with 71-76 GHz high-electron-mobility- transistor amplifiers followed by a low-loss radio frequency laminate-based grounded-coplanar-waveguide-to-WR-12 transition in order to enable broadband wireless communications over longer medium-range distances. © 2012 IEEE.
    view abstract10.1109/MWP.2012.6474105
  • Integration platform for 72-GHz photodiode-based wireless transmitter
    Bouhlal, B. and Lutzmann, S. and Palandöken, M. and Rymanov, V. and Stöhr, A. and Tekin, T.
    Proceedings of SPIE - The International Society for Optical Engineering 8259 (2012)
    Microwave photonics can provide superior advantages towards ultra-wideband wireless communications. In this work, we present an integration platform for 72GHz photodiode based wireless transmitter. The placement and positioning of discrete LNA and PA components, the bias-tee design parameters of photodiode, LNA and PA, and the design parameters for low-loss transition from CPW output of amplified electrical signal at the output of PA to E-band WR12 rectangular waveguide have to be carefully determined. We present general design principles of 72GHz photodiode integration platform. Further, we compare different substrates, which have been implemented into the platform, based on numerical results. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
    view abstract10.1117/12.909726
  • Low phase noise and frequency tunable 95-115 GHz photonic LO based upon DSB-SC modulation in an MZM and FWM in an UL-SOA
    Garcia, A. and Pillet, G. and Manager, L. and Morvan, L. and Babiel, S. and Fedderwitz, S. and Stöhr, A.
    2012 IEEE International Topical Meeting on Microwave Photonics, MWP 2012 - Proceedings (2012)
    We demonstrate a low-phase noise frequency-tunable photonic source for generating 100 GHz W-band signals. The source offers up to twelve times optical multiplication by exploiting nonlinearities in MZM and FWM in UL-SOA. Wide frequency tuning (95-115 GHz) with average output power of -24 dBm @ 4.18 mA photocurrent and output power variations <0.5 dB is demonstrated. The absolute phase noise of the W-band signals is measured to be <-91 dBc/Hz at 10 kHz. By using an optical reference LO, the residual phase noise from the photonic source is confirmed to be even <-103 dBc/Hz at 10 kHz offset. © 2012 IEEE.
    view abstract10.1109/MWP.2012.6474079
  • Quasi-hermetic photodiode module featuring a WR12 output for 71-76 GHz Radio-over-Fibre applications
    Flammia, I. and Babiel, S. and Leonhardt, C.C. and Honecker, J. and Steffan, A.G. and Stöhr, A.
    2012 IEEE International Topical Meeting on Microwave Photonics, MWP 2012 - Proceedings (2012)
    An E-Band quasi-hermetic photodiode module featuring a WR12 rectangular waveguide output has been developed using an RF transition implemented on ROGERS 5880 laminate. Its simulated maximum group delay deviation of less than 1 ps makes it suitable as wireless transmitter for Radio-over-Fibre (RoF) applications. The manufactured prototype exhibits a flat frequency response with a maximum variation < 1 dB within the band of interest (71-76 GHz). The maximum measured output power is -12.5 dBm, while the 1-dB compression point is at 9 mA, with -13.5 dBm of corresponding RF power. Error-free 1 Gb/s RoF transmission (BER< 10-9) has been demonstrated, with only 1.2 dB of measured power penalty over the 71-76 GHz band. © 2012 IEEE.
    view abstract10.1109/MWP.2012.6474107
  • High data rate radio over fiber technologies
    Stöhr, A. and Jäger, D.
    IEEE Photonic Society 24th Annual Meeting, PHO 2011 (2011)
    This paper presents photonic technologies enabling high data rate (>10 Gb/s) wireless access systems operating within the E-band (60-90 GHz) and the W-band (75-115 GHz). © 2011 IEEE.
    view abstract10.1109/PHO.2011.6110491
  • Novel E-band (71-76 GHz) photodiode module featuring a hermetic grounded-coplanar-waveguide-to-rectangular-waveguide transition
    Flammia, I. and Leonhardt, C.C. and Honecker, J. and Steffan, A.G. and Stöhr, A.
    2011 IEEE International Topical Meeting on Microwave Photonics - Jointly Held with the 2011 Asia-Pacific Microwave Photonics Conference, MWP/APMP 2011 (2011)
    This paper presents a novel concept of a hermetic E-Band Photodiode (PD) Transmitting Module for Radio-over-Fiber (RoF) applications. A commercial PD chip with 50 Ω coplanar waveguide (CPW) output is wire-bonded to a 50 Ω grounded coplanar waveguide (GCPW) based on ROGERS RT/Duroid 5880 substrate. From the GCPW board a hermetic transition that makes use of a double-slot coupling approach is designed and optimized for the 71-76 GHz band. This concept allows to efficiently coupling the electrical power delivered by the PD chip to a Rectangular Waveguide WR-12 output with an insertion loss of only 3 dB. © 2011 IEEE.
    view abstract10.1109/MWP.2011.6088757
  • Optical generation of low-phase noise microwave signals using nonlinear MZM and ultra-long SOA
    Garcia, A. and Fedderwitz, S. and Stöhr, A.
    SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference Proceedings (2011)
    We propose and demonstrate a tunable 50 GHz photonic synthesizer using nonlinearities in a Mach-Zehnder modulator (MZM) in conjunction with the four-wave mixing (FWM) effect in an ultra-long semiconductor optical amplifier (UL-SOA). The operation principle is based on an external modulation scheme using a low phase noise local oscillator (LO) source to multiply the LO frequency in the optical domain. We experimentally demonstrate tunable and low phase noise millimeter-wave (mm-wave) signal generation up to 50 GHz using a low frequency reference LO source. A multiplication of eight-times the LO frequency has been achieved resulting from the nonlinear behavior of the MZM in conjunction with the UL-SOA. Phase noise measurements of the fundamental LO frequency as well as of the generated mm-wave signal with a multiplication factor of N=8 have shown phase noise levels of -96 dBc/Hz and -78 dBc/Hz at 10 kHz offset from the carrier, respectively. © 2011 IEEE.
    view abstract10.1109/IMOC.2011.6169375
  • Millimeter-wave photonic components for broadband wireless systems
    Stöhr, A. and Babiel, S. and Cannard, P.J. and Charbonnier, B. and Van Dijk, F. and Fedderwitz, S. and Moodie, D. and Pavlovic, L. and Ponnampalam, L. and Renaud, C.C. and Rogers, D. and Rymanov, V. and Seeds, A. and Steffan, A.G. and Umbach, A. and Weis, M.
    IEEE Transactions on Microwave Theory and Techniques 58 (2010)
    We report on advanced millimeter-wave (mm-wave) photonic components for broadband radio transmission. We have developed self-pulsating 60-GHz range quantum-dash FabryProt mode-locked laser diodes (MLLD) for passive, i.e., unlocked, photonic mm-wave generation with comparably low-phase noise level of -76 dBc/Hz @ 100-kHz offset from a 58.8-GHz carrier. We further report on high-frequency 1.55-μm waveguide photodiodes (PD) with partially p-doped absorber for broadband operation f3 dB ∼ 70-110 GHz) and peak output power levels up to +4.5 dBm @ 110 GHz as well as wideband antenna integrated photomixers for operation within 30300 GHz and peak output power levels of -11 dBm @ 100 GHz and 6-mA photocurrent. We further present compact 60-GHz wireless transmitter and receiver modules for wireless transmission of uncompressed 1080p (2.97 Gb/s) HDTV signals utilizing the developed MLLD and mm-wave PD. Error-free (BER =10 -9, 2 31 -1 PRBS, NRZ) outdoor wireless transmission of 3 Gb/s over 25 m is demonstrated, as well as wireless transmission of uncompressed HDTV signals in the 60-GHz band. Finally, an advanced 60-GHz photonic wireless system offering record data throughputs and spectral efficiencies is presented. For the first time, we demonstrate photonic wireless transmission of data throughputs up to 27.04 Gb/s (EVM 17.6%) using a 16-QAM OFDM modulation format resulting in a spectral efficiency as high as 3.86 b/s/Hz. Wireless experiments were carried out within the regulated 57-64-GHz band in a lab environment with a maximum transmit power of -1 dBm and 23 dBi gain antennas for a wireless span of 2.5 m. This span can be extended to some 100 m when using high-gain antennas and higher transmit power levels. © 2006 IEEE.
    view abstract10.1109/TMTT.2010.2077470
  • Opto-electronic dual-loop 50 GHz oscillator with wide tunability and low phase noise
    Fedderwitz, S. and Stöhr, A. and Babiel, S. and Rymanov, V. and Jäger, D.
    Proceedings - 2010 IEEE International Topical Meeting on Microwave Photonics, MWP 2010 (2010)
    We propose and demonstrate a 50 GHz opto-electronic dual-loop oscillator with low phase noise of -95 dBc/Hz at 10 kHz offset from a 50 GHz carrier and a frequency tunability of more than 100 MHz. ©2010 IEEE.
    view abstract10.1109/MWP.2010.5664675
  • Optoelectronic K-band oscillator with gigahertz tuning range and low phase noise
    Fedderwitz, S. and Stöhr, A. and Babiel, S. and Rymanov, V. and Jager, D.
    IEEE Photonics Technology Letters 22 (2010)
    We propose and demonstrate a K-band optoelectronic oscillator with ultralow phase noise performance and a frequency tuning range exceeding 1 GHz. The operation principle is based upon using two parallel optoelectronic loops with similar but not equal length and an electrical phase shifter for frequency tuning. We experimentally demonstrate tunable microwave signal generation within 20.7-21.8 GHz with a coarse frequency resolution of ∼100 MHz. Fine tuning of the generated signal within a range of ±5 MHz is also achieved. The linewidth and phase noise of the generated microwave signal are <3 Hz and - 105 dBc/Hz at 10-kHz offset, respectively. Within the full gigahertz tuning range, the phase noise and output power of the generated microwave signal varies by only ±1.5 and <1 dB, respectively. © 2010 IEEE.
    view abstract10.1109/LPT.2010.2064762
  • Photonic millimeter-wave generation and its applications in high data rate wireless access
    Stöhr, A.
    Proceedings - 2010 IEEE International Topical Meeting on Microwave Photonics, MWP 2010 (2010)
    Microwave Photonics is widely considered as a disruptive technology for high data rate wireless communications. This paper discusses technological trends in enabling photonic solutions for high data rate wireless access systems operating in the millimeter-wave regime. Besides technical achievements, a focus is also put on worldwide regulations for wireless communications in the E-band (60-90 GHz). ©2010 IEEE.
    view abstract10.1109/MWP.2010.5664246
  • Quantum dash mode-locked lasers for millimeter wave signal generation and transmission
    Van Dijk, F. and Charbonnier, B. and Constant, S. and Enard, A. and Fedderwitz, S. and Formont, S. and Lealman, I.F. and Lecoche, F. and Lelarge, F. and Moodie, D. and Ponnampalam, L. and Renaud, C. and Robertson, M.J. and Seeds, A.J. and Stöhr, A. and Weiß D, M.
    2010 23rd Annual Meeting of the IEEE Photonics Society, PHOTINICS 2010 (2010)
    In this paper we present the remarkable characteristics of quantum dash mode-locked lasers and how they could be used for low phase noise signal generation, for high data rate wireless transmission and radar in the millimeter wave frequency range. ©2010 IEEE.
    view abstract10.1109/PHOTONICS.2010.5698821
  • Thermopile antennas for detection of millimeter waves
    Szentpáli, B. and Basa, P. and Fürjes, P. and Battistig, G. and Bársony, I. and Károlyi, G. and Berceli, T. and Rymanov, V. and Stöhr, A.
    Applied Physics Letters 96 (2010)
    A thermopile structure is proposed for the detection of microwave/millimeter wave radiation. The thermopairs in the suggested linear arrangement function as antennas. 5.58 V/W responsivity was achieved at 100 GHz with 40 serial connected thermopairs. The experimentally observed polarity and frequency dependence convincingly verify the proper detector operation. © 2010 American Institute of Physics.
    view abstract10.1063/1.3374445
  • microwave photonics

  • optoelectronics

  • photodiodes

  • photonic transmitter

  • photonics

  • wireless communications

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