Showing papers by "Alwyn J. Seeds published in 1998"
TL;DR: In this article, a millimetre-wave optical signal generation by heterodyning two fiber grating lasers is demonstrated, and the resulting beat signal has an extremely narrow linewidth (< 50 kHz, is continuously tunable (0 - 40 GHz) and exhibits negligible chirp under direct 2.6 Gbit/s modulation.
Abstract: Millimetre-wave optical signal generation by heterodyning two fibre grating lasers is demonstrated. The resulting beat signal has an extremely narrow linewidth (< 50 kHz), is continuously tunable (0 – 40 GHz) and exhibits negligible chirp under direct 2.6 Gbit/s modulation.
37 citations
TL;DR: In this paper, the first quantum-confined Stark effect tuned two-section ridge waveguide laser fabricated by postgrowth band gap engineering techniques was reported. And the most uniform response was achieved for a field effect tuned laser.
Abstract: Conventional tunable semiconductor lasers tuned by the carrier induced effect suffer from intrinsically nonuniform optical frequency modulation (FM) response due to the associated thermal effect. Electric field effect tuned lasers involving no current injection, offer intrinsically uniform FM response. We report here the first quantum-confined Stark effect tuned two-section ridge waveguide laser fabricated by postgrowth band gap engineering techniques. An highly uniform FM response, within /spl plusmn/3 dB from 30 kHz to 6 GHz, is achieved, independent of laser output power, the widest and most uniform response yet reported for a field effect tuned laser. The residual intensity modulation is less than 5% for 4.5-GHz peak frequency deviation.
23 citations
07 Jun 1998
TL;DR: In this article, a millimetre-wave optical signal generation by heterodyning two semiconductor fiber grating lasers was demonstrated for the first time, and the resulting beat signal has an extremely narrow linewidth (<100 kHz.
Abstract: Millimetre-wave optical signal generation by heterodyning two semiconductor fibre grating lasers is demonstrated for the first time. The resulting beat signal, has an extremely narrow linewidth (<100 kHz), is continuously tuneable (0-40 GHz) and exhibits negligible chirp under direct 2.6 Gbit/s modulation.
21 citations
01 Dec 1998
TL;DR: In this paper, the authors discuss architectures for providing broadband wireless access using optical fiber signal transport systems, including microwave modulated optical signal generation using optical phase lock loops and fiber grating lasers, and signal detection using optically controlled heterostructure phototransistors.
Abstract: The paper will discuss architectures for providing broadband wireless access using optical fibre signal transport systems. Recent advances in microwave modulated optical signal generation using optical phase lock loops and fibre grating lasers and in signal detection using optically controlled heterostructure phototransistors will also be described.
11 citations
01 Dec 1998
TL;DR: In this article, a diode-laser optical phase-locked loop (OPLL) sub-system has been constructed for evaluation in a proof-of-concept optical beamforming system.
Abstract: Coherent optical beamforming is particularly advantageous in multi-beam mobile phased array communications. Systems of this type employ a pair of phase locked optical carriers with a difference frequency equal to the required microwave signal. In this work a packaged diode-laser optical phase locked loop (OPLL) sub-system has been constructed for evaluation in a proof-of-concept optical beamforming system. The loop has been implemented with laser diodes, micro-optics and wide bandwidth electronics to give optimum phase noise performance.
8 citations
TL;DR: In this article, the first reported optical phase-locked loop module has been designed and constructed for use in coherent optical beamforming systems using micro-optics, wideband feedback electronics and custom diode lasers with a suitable FM response.
Abstract: The first reported optical phase-locked loop module has been designed and constructed for use in coherent optical beamforming systems. It has been implemented using micro-optics, wideband feedback electronics and custom diode lasers with a suitable FM response. The module has an LO tuning range of 7-14 GHz and a total phase error variance of 0.05 rad/sup 2/.
6 citations
03 Nov 1998
TL;DR: In this paper, a diode-laser OPLL sub-system has been constructed for evaluation in a proof-of-concept coherent optical beamforming system, where the loop has been implemented with narrow linewidth laser diodes, micro-optics and wide bandwidth electronics to give optimum phase noise performance.
Abstract: A packaged diode-laser OPLL sub-system has been constructed for evaluation in a proof-of-concept coherent optical beamforming system. The loop has been implemented with narrow linewidth laser diodes, micro-optics and wide bandwidth electronics to give optimum phase noise performance. The laser diodes are designed for wide bandwidth and high FM-efficiency, while the main challenge in the construction of the packaged OPLL is the realization of a high gain loop, with a small propagation delay. A total phase variance of 0.05 rad2 has been achieved, and that within the 15 MHz system bandwidth is 0.0007 rad2. The OPLL can operate with LO frequencies from 7-15 GHz. This paper details the performance of the completed OPLL module together with key results for the custom FM lasers designed and fabricated for use within it.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
5 citations
01 Jan 1998
TL;DR: Techniques for providing broadband wireless access using millimetre-wave over fibre systems using optical phase lock loop techniques and in signal detection using optically controlled heterojunction phototransistors are reviewed.
Abstract: The paper reviews technologies for providing broadband wireless access using millimetre-wave over fibre systems. Recent advances in modulated signal generation using optical phase lock loop techniques and in signal detection using optically controlled heterojunction phototransistors are also described.
2 citations
29 Sep 1998
TL;DR: In this paper, the authors reported the first post-growth band-gap engineered, quantum-confined Stark effect (QCSE) tuned two-section ridge waveguide laser with the widest and most uniform frequency modulation bandwidth (30 kHz to 6 GHz /spl plusmn/3 dB) yet reported for field effect tuned laser.
Abstract: Conventional semiconductor lasers tuned by the carrier-induced effect (CIE) suffer from intrinsically non-uniform optical frequency modulation (FM) response due to the associated thermal effect Electric field effect tuned lasers involving no current injection, offer intrinsically uniform FM response We report the first post-growth band-gap engineered, quantum-confined Stark effect (QCSE) tuned two-section ridge waveguide laser, having the widest and most uniform frequency modulation bandwidth (30 kHz to 6 GHz /spl plusmn/3 dB) yet reported for field effect tuned lasers The uniform FM response is independent of laser output power, and residual intensity modulation is less than 5% for 45 GHz peak frequency deviation
2 citations
12 Oct 1998
TL;DR: In this paper, the authors reported the first post-growth band-gap engineered, quantum-confined Stark effect (QCSE) tuned two-section ridge waveguide GaAs-AlGaAs MQW laser having the widest and most uniform frequency modulation bandwidth (30 kHz to 6 GHz/spl plusmn/3 dB) yet reported for field effect tuned lasers.
Abstract: We report the first post-growth band-gap engineered, quantum-confined Stark effect (QCSE) tuned two-section ridge waveguide GaAs-AlGaAs MQW laser, having the widest and most uniform frequency modulation bandwidth (30 kHz to 6 GHz/spl plusmn/3 dB) yet reported for field effect tuned lasers.
2 citations
20 Sep 1998
TL;DR: In this article, the first post-growth band-gap engineered, quantum-confirmed Stark effect (QCSE) tuned two-section ridge waveguide laser, having the most uniform frequency modulation response (spl plusmn/3 dB) in the widest modulation bandwidth (30 kHz to 6 GHz) yet reported for QCSE tuned lasers, was reported.
Abstract: We report on the first post-growth band-gap engineered, quantum-confirmed Stark effect (QCSE) tuned two section ridge waveguide laser, having the most uniform frequency modulation response (/spl plusmn/3 dB) in the widest modulation bandwidth (30 kHz to 6 GHz) yet reported for QCSE tuned lasers.
01 Dec 1998
TL;DR: The first post-growth band gap engineered, quantum-confined Stark effect (QCSE) tuned two-section ridge waveguide MQW laser was reported in this article, with the widest and most uniform frequency modulation bandwidth (30 kHz to 6 GHz/spl plusmn/3 dB) yet reported for field effect tuned laser.
Abstract: We report the first post-growth band-gap engineered, quantum-confined Stark effect (QCSE) tuned two section ridge waveguide MQW laser, having the widest and most uniform frequency modulation bandwidth (30 kHz to 6 GHz/spl plusmn/3 dB) yet reported for field effect tuned lasers