Laser Receiver I.
Final rept. 6 Nov 72-30 Jun 73,
LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA PALO ALTO RESEARCH LAB
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An optical receiver for a brassboard 1000-MBPS laser communications system was designed, constructed, and tested. The communications system operated by polarization modulating a cw, single-frequency, green, optical carrier with a 1.5-GHz subcarrier. The subcarrier is quadriphase-shift-keyed by two independent 500-MBPS data streams. The optical receiver consists basically of two photomultiplier tubes of special design, together with associated optics, electronics, and mechanical hardware needed for operation. The phototubes are crossed-field photomultipliers having four stages of multiplication. The tubes had nearly flat frequency response over the 1- to 2-GHz band in which the major portion of the signal spectrum is contained. When the receiver was tested as a part of the complete brassboard, system performance within 5.4 dB of theoretical was obtained. Most of the performance degradation was due to other aspects of the system. The major problem of the program was that of achieving and maintaining the necessary performance from the phototubes. The tube development program never produced two tubes with suitable and stable characteristics. The main recommendations are for further work on the phototube development. There does not appear to be any fundamental reason, however, which would prevent attainment of a tube with suitable characteristics. Author
- Lasers and Masers
- Non-Radio Communications