Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Patent
1986-06-11
1993-06-29
Gregory, Bernarr E.
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
359118, 359164, 359173, 359183, 359188, 359195, H04B 1002
Patent
active
052239675
ABSTRACT:
There is provided by this invention a secure fiber optic communication system based on the Sagnac interferometer that allows multiple authorized users to communicate on the system by modulation and detection of two counterpropagating light beams. The security of the system is based on a combination of the information being modulated on the relative phase difference between the counterpropagating light beams and the low coherence length of the light source. In order for an intruder to intercept the signal, both counterpropagating beams must be accessed and the pathlength of the two beams matched to within a few coherence lengths of the light source so that an amplitude modulated output signal may be constructed. The system is further comprised of a random pathlength generator used to randomly vary the relative pathlength of the two counterpropagating beams. A light level alarm is provided that detects changes in the light level within the system. If the signal level changes sufficiently, the light level alarm shuts down the system.
REFERENCES:
patent: 2531951 (1950-11-01), Shamos et al.
patent: 2707749 (1955-05-01), Mueller
patent: 3366792 (1968-01-01), Ohm
patent: 3408498 (1968-10-01), Ohm
patent: 3495189 (1970-02-01), Craw
patent: 3584220 (1971-06-01), Nomura et al.
patent: 3828185 (1974-08-01), Vandling
patent: 3936748 (1976-02-01), Bomke
patent: 4002896 (1977-01-01), Davies et al.
patent: 4187404 (1980-02-01), Deman et al.
patent: 4433915 (1984-02-01), Hanse
patent: 4434510 (1984-02-01), Lemelson
patent: 4456376 (1984-06-01), Carrington et al.
patent: 4456377 (1984-06-01), Shaw et al.
patent: 4479264 (1984-10-01), Lockett et al.
patent: 4482980 (1984-11-01), Korowitz et al.
patent: 4540243 (1985-09-01), Fergason
patent: 4642804 (1987-02-01), Personick
patent: 4658394 (1987-04-01), Cheng et al.
patent: 4736465 (1988-04-01), Bobey et al.
Nagata et al, "Intra-Office Optical Fiber Transmission Systems"; Rev. of the Electrical Comm. Labs; vol. 27, No. 11-12; Nov.-Dec., 1979; pp. 1057-1068.
Cheng et al, "Subscriber Loop Architecture"; Technical Digest; No. 75, Sep. 1984, pp. 9-10.
Gregory Bernarr E.
McDonnell Douglas Corporation
Scholl John P.
Stout Donald E.
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