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Your search keyword '"Seeds, A. J."' showing total 308 results
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308 results on '"Seeds, A. J."'

1. High performance waveguide uni-travelling carrier photodiode grown by solid source molecular beam epitaxy

Author

Lin, Xiaoli, Natrella, Michele, Seddon, James, Graham, Chris, Renaud, Cyril C., Tang, Mingchu, Wu, Jiang, Liu, Huiyun, and Seeds, Alwyn J.

Subjects
Physics - Applied Physics, Physics - Optics
Abstract

The first waveguide coupled phosphide-based UTC photodiodes grown by Solid Source Molecular Beam Epitaxy (SSMBE) are reported in this paper. Metal Organic Vapour Phase Epitaxy (MOVPE) and Gas Source MBE (GSMBE) have long been the predominant growth techniques for the production of high quality InGaAsP materials. The use of SSMBE overcomes the major issue associated with the unintentional diffusion of zinc in MOVPE and gives the benefit of the superior control provided by MBE growth techniques without the costs and the risks of handling toxic gases of GSMBE. The UTC epitaxial structure contains a 300 nm n-InP collection layer and a 300 nm n++-InGaAsP waveguide layer. UTC-PDs integrated with Coplanar Waveguides (CPW) exhibit 3 dB bandwidth greater than 65 GHz and output RF power of 1.1 dBm at 100 GHz. We also demonstrate accurate prediction of the absolute level of power radiated by our antenna integrated UTCs, between 200 GHz and 260 GHz, using 3d full-wave modelling and taking the UTC-to-antenna impedance match into account. Further, we present the first optical 3d full-wave modelling of waveguide UTCs, which provides a detailed insight into the coupling between a lensed optical fibre and the UTC chip., Comment: 19 pages, 24 figures

Published
2019
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2. Optical communications-based platform uses Uni-Travelling-Carrier Photodiode for ultra-high resolution software-defined THz spectroscopy and reveals LiYF4:Ho intrinsic spectral line shape

Author

Hermans, Rodolfo I., Shams, Haymen, Seddon, James P., Seeds, Alwyn J., and Aeppli, Gabriel

Subjects
Physics - Instrumentation and Detectors, Physics - Optics
Abstract

High resolution (900 Hz full-width at half maximum) frequency domain spectroscopy near 0.2Terahertz is achieved using an exact frequency spacing comb-source in the optical communications band, filtering and photo-mixing in a custom Uni-Travelling-Carrier Photodiode (UTC-PD) for THz signal generation and coherent down-conversion for detection. Via time domain modulation of one of the comb lines, a fully controllable spectrometer can be defined in software, and this principle is demonstrated for magnetic field-free readout of the electronuclear spectrum for the Ho ions in \lihof, a material often used for demonstration experiments in quantum science. In particular, homogeneous and inhomogeneous contributions to the spectrum are readily separated.

Published
2019

3. Pilot-tone assisted 16-QAM photonic wireless bridge operating at 250 GHz

Author

Gonzalez-Guerrero, Luis, Shams, Haymen, Fatadin, Irshaad, Wu, John Edward, Fice, Martyn J., Naftaly, Mira, Seeds, Alwyn J., and Renaud, Cyril C.

Subjects
Electrical Engineering and Systems Science - Signal Processing
Abstract

A photonic wireless bridge operating at a carrier frequency of 250 GHz is proposed and demonstrated. To mitigate the phase noise of the free-running lasers present in such a link, the tone-assisted carrier recovery is used. Compared to the blind phase noise compensation (PNC) algorithm, this technique exhibited penalties of 0.15 dB and 0.46 dB when used with aggregated Lorentzian linewidths of 28 kHz and 359 kHz, respectively, and 20 GBd 16-quadrature amplitude modulation (QAM) signals. The wireless bridge is also demonstrated in a wavelength division multiplexing (WDM) scenario, where 5 optical channels are generated and sent to the Tx remote antenna unit (RAU). In this configuration, the full band from 224 GHz to 294 GHz is used. Finally, a 50 Gbit/s transmission is achieved with the proposed wireless bridge in single channel configuration. The wireless transmission distance is limited to 10 cm due to the low power emitted by the uni-travelling carrier photodiode used in the experiments. However, link budget calculations based on state-of-the-art THz technology show that distances >1000 m can be achieved with this approach., Comment: 13 pages, in Journal of Lightwave Technology

Published
2019
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4. Monolithic quantum-dot distributed feedback laser array on silicon

Author

Wang, Yi, Chen, Siming, Yu, Ying, Zhou, Lidan, Liu, Lin, Yang, Chunchuan, Liao, Mengya, Tang, Mingchu, Liu, Zizhuo, Wu, Jiang, Li, Wei, Ross, Ian, Seeds, Alwyn J., Liu, Huiyun, and Yu, Siyuan

Subjects
Physics - Optics, Physics - Applied Physics
Abstract

Electrically-pumped lasers directly grown on silicon are key devices interfacing silicon microelectronics and photonics. We report here, for the first time, an electrically-pumped, room-temperature, continuous-wave (CW) and single-mode distributed feedback (DFB) laser array fabricated in InAs/GaAs quantum-dot (QD) gain material epitaxially grown on silicon. CW threshold currents as low as 12 mA and single-mode side mode suppression ratios (SMSRs) as high as 50 dB have been achieved from individual devices in the array. The laser array, compatible with state-of-the-art coarse wavelength division multiplexing (CWDM) systems, has a well-aligned channel spacing of 20 0.2 nm and exhibits a record wavelength coverage range of 100 nm, the full span of the O-band. These results indicate that, for the first time, the performance of lasers epitaxially grown on silicon is elevated to a point approaching real-world CWDM applications, demonstrating the great potential of this technology.

Published
2018
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9. Inversion boundary annihilation in GaAs grown on On‐Axis Silicon (001) via Molecular Beam Epitaxy

Author

Yu, Xuezhe, primary, Li, Keshuang, additional, Yang, Junjie, additional, Lu, Ying, additional, Liu, Zizhuo, additional, Tang, Mingchu, additional, Jurczak, Pamela, additional, Park, Jae-Seong, additional, Deng, Huiwen, additional, Jia, Hui, additional, Dang, Manyu, additional, Sanchez, Ana M., additional, Beanland, Richard, additional, Li, Wei, additional, Han, Xiaodong, additional, Zhang, Jinchuan, additional, Wang, Huan, additional, Liu, Fengqi, additional, Chen, Siming, additional, Seeds, Alwyn J., additional, Smowton, Peter M., additional, and Liu, Huiyun, additional

Published
2021
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10. Co-Package Technology Platform for Low-Power and Low-Cost Data Centers

Author

Papatryfonos, Konstantinos, primary, Selviah, David R., additional, Maman, Avi, additional, Hasharoni, Kobi, additional, Brimont, Antoine, additional, Zanzi, Andrea, additional, Kraft, Jochen, additional, Sidorov, Victor, additional, Seifried, Marc, additional, Baumgartner, Yannick, additional, Horst, Folkert, additional, Offrein, Bert Jan, additional, Lawniczuk, Katarzyna, additional, Broeke, Ronald G., additional, Terzenidis, Nikos, additional, Mourgias-Alexandris, George, additional, Tang, Mingchu, additional, Seeds, Alwyn J., additional, Liu, Huiyun, additional, Sanchis, Pablo, additional, Moralis-Pegios, Miltiadis, additional, Manolis, Thanasis, additional, Pleros, Nikos, additional, Vyrsokinos, Konstantinos, additional, Sirbu, Bogdan, additional, Eichhammer, Yann, additional, Oppermann, Hermann, additional, and Tekin, Tolga, additional

Published
2021
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13. Transmission of wireless MIMO-type signals over single optical fiber without WDM

Author

Chhin-Pang Liu and Seeds, Alwyn J.

Subjects
Digital signal processors -- Usage, Fiber optics -- Analysis, MIMO communications -- Analysis, Microwaves -- Analysis, Phase modulation -- Analysis, Digital signal processor, Fiber optics, Business, Computers, Electronics, Electronics and electrical industries
Published
2010

17. A monolithic MQW InP-InGaAsP-based optical comb generator

Author

Renaud, Cyril C., Pantouvaki, Marianna, Gregoire, Sylvie, Lealman, Ian, Cannard, Paul, Cole, Simon, Moore, Ron, Gwilliam, Russell, and Seeds, Alwyn J.

Subjects
Frequency modulation -- Analysis, Photonics -- Research, Quantum wells -- Research, Semiconductor lasers -- Design and construction, Business, Computers, Electronics, Electronics and electrical industries
Abstract

A monolithic optical-frequency comb generator based on multisection quaternary/quaternary eight-quantum-well InP-InGaAsP material is presented. Findings reveal the production of a number of lines with spacing exactly equal to the modulation frequency, differential phase noise between adjacent lines of -82 dBc/Hz at 1-kHz offset and a potential comb spectrum width of up to 2 THz.

Published
2007

20. Microwave photonics

Author

Seeds, Alwyn J.

Subjects
Photonics -- Equipment and supplies, Fiber optics -- Equipment and supplies, Signal processing -- Equipment and supplies, Phased array antennas -- Design and construction, Business, Computers, Electronics, Electronics and electrical industries
Abstract

The low-loss wide-bandwidth capability of opto-electronic systems makes them attractive for the transmission and processing of microwave signals, while the development of high-capacity optical communication systems has required the use of microwave techniques in optical transmitters and receivers. These two strands have led to the development of the research area of microwave photonics. This paper describes the development of microwave photonic devices, describes their systems applications, and suggests likely areas for future development. Index Terms--Microwave photonics, modulators, optical fiber, optical signal processing, phased array, photodetectors, semiconductor lasers.

Published
2002

31. An integrated heterojunction bipolar transistor cascode opto-electronic mixer

Author

Betser, Yoram, Lasri, Jacob, Sidorov, Victor, Cohen, Shimon, Ritter, Dan, Orenstein, Meir, Eisenstein, Gadi, Seeds, Alwyn J., and Madjer, Asher

Subjects
Mixers (Electronics) -- Evaluation, Bipolar transistors -- Usage, Optoelectronic devices -- Evaluation, Optoelectronics -- Equipment and supplies, Business, Computers, Electronics, Electronics and electrical industries
Abstract

An integrated electrically pumped opto-electronic mixer consisting of two InP/GaInAs heterojunction bipolar transistors in a cascode configuration is demonstrated. Intrinsic downconversion gains of 18.2 and 8.9 dB at RF optical modulation frequencies of 3 and 9.5 GHz were obtained. The performance of the cascode mixer and a single heterojunction bipolar transistor (HBT) opto-electronic mixer are compared. The performance of the cascode mixer was superior to the single HBT mixer, mainly at high frequencies. Up and down mixing conversion gains were measured and found comparable. A simulation was carried out by solving the nonlinear differential equations that correspond to the large-signal equivalent circuit. The results of the simulation enabled us to identify the principal nonlinear components in the equivalent circuit. Index Terms - Cascode, conversion gain, mixer, opto-electronic, photo-HBT.

Published
1999

32. Tunable THz Signal Generation and Radioover-Fiber Link based on an Optoelectronic Oscillator-driven Optical Frequency Comb

Author

Hasanuzzaman, G.K.M., Shams, Haymen, Renaud, Cyril C., Mitchell, John, Seeds, Alwyn J., Iezekiel, Stavros, and Iezekiel, Stavros [0000-0002-5933-3489]

Subjects
Physics, Optical fiber, business.industry, Bandwidth (signal processing), 02 engineering and technology, Atomic and Molecular Physics, and Optics, law.invention, 020210 optoelectronics & photonics, Radio over fiber, Band-pass filter, law, Phase noise, 0202 electrical engineering, electronic engineering, information engineering, Optoelectronics, Photonics, business, Optical filter, Phase modulation
Abstract

We propose and demonstrate experimentally a photonic THz signal generation technique based on a tunable optoelectronic oscillator (OEO), and its application in a radio over fiber (RoF) link. The OEO's is tuned by varying the bandwidth of a tunable optical bandpass filter (TOBF) that is cascaded with a phase modulator (PM). The resulting tunable microwave photonic filter is used to generate OEO oscillations from 6.58 GHz up to 18.36 GHz (with a phase noise of $\rm\leq -103dBc/Hz$ at 10 kHz offset from the carrier frequency). The OEO is subsequently used to drive an optical comb, generating 22 comb lines with a frequency spacing of 17.33 GHz covering a bandwidth of 360 GHz within a 20 dB envelope. By selecting two optical comb lines with a wavelength selective switch (WSS) and beating them in a uni-traveling carrier photodiode (UTC-PD), THz signals are generated at 101.5 GHz and 242.6 GHz with phase noise of -90 dBc/Hz and -78 dBc/Hz, respectively at 10 kHz offset from carrier frequency. Tunable mm-wave and THz signals can be generated either by changing the OEO oscillation frequency or the selected comb lines. Using the OEO driven OFCG, we implemented a RoF link at 242.6 GHz with a data rate of 24 Gbps over a wireless distance of 30 cm and with a bit error rate (BER) below the hard decision forward error correction (FEC) limit of $3.8\times10^-3$. This method allows the creation of an allphotonic frequency reconfigurable THz signal generator and RoF system. 1 1

Published
2019

33. Generation of continuous wave terahertz frequency radiation from metal-organic chemical vapour deposition grown Fe-doped InGaAs and InGaAsP.

Author

Mohandas, Reshma A., Freeman, Joshua R., Rosamond, Mark C., Hatem, Osama, Chowdhury, Siddhant, Ponnampalam, Lalitha, Fice, Martyn, Seeds, Alwyn J., Cannard, Paul J., Robertson, Michael J., Moodie, David G., Cunningham, John E., Giles Davies, A., Linfield, Edmund H., and Dean, Paul

Subjects
CONTINUOUS wave lasers, INDIUM gallium arsenide, CHEMICAL vapor deposition, BRAGG gratings, EMISSION spectroscopy
Abstract

We demonstrate the generation of continuous wave terahertz (THz) frequency radiation from photomixers fabricated on both Fe-doped InGaAs and Fe-doped InGaAsP, grown by metal-organic chemical vapor deposition. The photomixers were excited using a pair of distributed Bragg reflector lasers with emission around 1550 nm, and THz radiation was emitted over a bandwidth of greater than 2.4 THz. Two InGaAs and four InGaAsP wafers with different Fe doping concentrations were investigated, with the InGaAs material found to outperform the InGaAsP in terms of emitted THz power. The dependencies of the emitted power on the photomixer applied bias, incident laser power, and material doping level were also studied. [ABSTRACT FROM AUTHOR]

Published
2016
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35. Optical frequency modulation links: theory and experiments

Author

Cai, Bo and Seeds, Alwyn J.

Subjects
Optical communications -- Research, Frequency modulation -- Research, Microwave devices -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

In this paper, the first theoretical analysis and experimental realization of an optical frequency modulation coherent detection (FMCD) link working at microwave frequencies is reported. Advantages over conventional optical intensity modulation direct detection (IMDD) links in terms of reduced effects of fiber nonlinearity, facilitation of multichannel operation, and bandwidth/signal-to-noise ratio (SNR) tradeoffs are identified. A detailed theoretical analysis of the SNR of FMCD links is carried out and compared to that for IMDD links. In the experimental FMCD link, a novel source laser tuning technique, based on the quantum confined Stark effect, is used. The experimental results are presented and compared with the predictions of the theoretical analysis. Index Terms - Coherent optical communication, microwave photonics, optical fiber links, quantum well, semiconductor laser.

Published
1997

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