MICROWAVE OPTICAL RECEIVER TECHNIQUES.
Final technical rept. 1 Jun 65-1 Jun 66,
SYLVANIA ELECTRONIC SYSTEMS-WEST MOUNTAIN VIEW CA ELECTRONIC DEFENSE LABS
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The objective of this program is to conduct applied research to compare quantitatively, both experimentally and theoretically, the performance characteristics of both direct and heterodyne receivers for microwave-modulated light which has traversed an outdoor path through the atmosphere and to determine the optimum type of optical modulation and receiver systems to use for various specific applications. The experimental operation of both direct-detection and optical heterodyne receivers capable of microwave bandwidths has been achieved over a 300-foot outdoor path, thus subjecting the systems to a non-laboratory environment and short-range atmospheric turbulence effects. Ideal, signal-shot-noise-limited performance was obtained in the direct-detection systems using a multiplier-traveling-wave phototube with L-band optical modulation. A wideband, crossed-field photomultiplier and a microwave avalanche diode were also evaluated. The optical heterodyne performance was approximately one order of magnitude below the quantum noise limit, due to non-ideal spatial coherence arising from atmospheric turbulence and active optical elements. Detailed real-world experimental characteristics of the system components were obtained.
- Radio Communications