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Proceedings Paper

Improvement of coherent homodyne detection performance using time-gated amplification and LiNbO3 optical 90o hybrid
Author(s): Pak S. Cho; Geof Harston; Chris J. Kerr; Art Greenblatt; Arkady Kaplan; Yaakov Achiam; Isaac Shpantzer
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Paper Abstract

Coherent homodyne detection using local laser oscillator is an important technique for applications requiring high receiver sensitivity. Conventional homodyne detection uses a continuous-wave (CW) local laser oscillator (LO) in which the only adjustable parameter is its average power. A pulsed LO with repetition rate same as the data symbol rate is proposed which provides new degree of freedom in receiver design, namely, its pulse shape and duty cycle. It is shown that pulsed LO is overall effective in enhancing receiver sensitivity compared with CW LO. We have investigated and compared the performance of coherent detection of 12.5 Gb/s binary phase-shift-keyed signals using integrated LiNbO3 optical 90° hybrid with pulsed and CW LO for different receiver bandwidths. Our results showed that pulsed LO provide at least 2 dB in sensitivity improvement. We also observed that pulsed LO is effective in reshaping broadened signal pulses. Our simulation results agreed well with experiment and predicted that for a given signal and receiver bandwidth there is an optimal LO pulse width that gives maximum eye opening. Our simulation results also showed that pulsed LO is potentially effective in reducing penalty of pulse smearing as a result of beam steering impairment in free-space laser communications.

Paper Details

Date Published: 15 September 2004
PDF: 12 pages
Proc. SPIE 5403, Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense III, (15 September 2004); doi: 10.1117/12.541569
Show Author Affiliations
Pak S. Cho, CeLight, Inc. (United States)
Geof Harston, CeLight, Inc. (United States)
Chris J. Kerr, CeLight, Inc. (United States)
Art Greenblatt, CeLight, Inc. (United States)
Arkady Kaplan, CeLight, Inc. (United States)
Yaakov Achiam, CeLight, Inc. (United States)
Isaac Shpantzer, CeLight, Inc. (United States)

Published in SPIE Proceedings Vol. 5403:
Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense III
Edward M. Carapezza, Editor(s)

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