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Proceedings Paper

Coherent modulating retroreflector system
Author(s): Peter G. Goetz; Rita Mahon; Lee Swingen; Jennifer L. Witkowsky; William S. Rabinovich
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Paper Abstract

One unusual aspect of a modulating retroreflector (MRR) system is that the interrogating laser and the receiver are collocated. This fact, plus the lack of optical amplifiers capable of low data rates, makes the use of a coherent receiver attractive. By splitting off a portion of the interrogating beam, a local oscillator (LO) is made available to mix with the returning signal beam. This self-homodyning is accomplished at very low cost, without the need for an additional laser or an optical phase-locked loop. Changes are only required in the interrogator/receiver, so increased ranges could be realized with no changes to MRR transmitters that have already been developed. A similar method could be used to realize a heterodyne system. To cancel the effects of atmospheric turbulence, a phase-diversity receiver configuration was used. A maximum gain of about 17 dB was observed, limited by saturation of the receiver electronics. The use of coherent interrogator/receivers can increase receiver sensitivity, extending the range of existing systems and showing great promise for modulating retroreflector links.

Paper Details

Date Published: 20 October 2004
PDF: 7 pages
Proc. SPIE 5550, Free-Space Laser Communications IV, (20 October 2004); doi: 10.1117/12.561703
Show Author Affiliations
Peter G. Goetz, Naval Research Lab. (United States)
Rita Mahon, Naval Research Lab. (United States)
Lee Swingen, Naval Research Lab. (United States)
Jennifer L. Witkowsky, Naval Research Lab. (United States)
William S. Rabinovich, Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 5550:
Free-Space Laser Communications IV
Jennifer C. Ricklin; David G. Voelz, Editor(s)

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