| 摘要 |
A secure fiber optic communication system (30, 120, 130, 170, 190, 220, 250, 270, 330, 380, 685, 700, 900, 1100, 1200 or 1290) capable of tens of gigabits data transfer rates that utilizes a pair of single mode fiber optic cables (110 and 112) in combination with one or more light sources (36; 314 and 316; 388, 390, and 392; 1127 and 1133; 1201 and 1247; or 1301 and 1315) phase modulators (58; 286 and 310; 418, 420, and 422; 1101 and 1103, or 1303 and 1317) detectors (76, 310 and 328; 424, 426, and 428; 1109, 1111, 1113, and 1115, or 1307 and 1307) and polarization scrambling elements (40 and 71; 288 and 308; 394, 396, 398, 430, 432, and 434) to form a Sagnac interferometer. The phase modulator (58; 286 and 310; 418, 420, and 422; 1101 and 1103, or 1303 and 1317) is driven so that counter propagating light beams (52, 54, 58, and 68; or 438 and 440) in the Sagnac loop (56, 290, 306, 436, 1304 or 1314) experience a different optical path as they pass through the loop. When the two beams (52, 54, 58, and 68; or 438 and 440) are recombined on the central beamsplitter (44, 274, 302, 400, 402, 404, 1105, or 1107) of the Sagnac loop (56, 290, 306, 436, 1304 or 1314), the two beams (52, 54, 58, and 68; or 438 and 440) interfere with each other and the data impressed as phase modulation on the light beams (52, 54, 58, and 68; or 438 and 440) by the phase modulator (58; 286 and 310; 418, 420, and 422; 1101 and 1103, or 1303 and 1317) is recovered as amplitude modulation on the output detector of the Sagnac interferometer. The system (30, 120, 130, 170, 190, 220, 250, 270, 330, 380, 685, 700, 900, 1100, 1200 or 1290) can be configured to operate full duplex on two optical fibers by using light at different wavelengths or time division multiplexing data. The system (30, 120, 130, 170, 190, 220, 250, 270, 330, 380, 685, 700, 900, 1100, 1200 or 1290) can also be configured as a multi-node network. Although the systems (30, 120, 130, 170, 190, 220, 250, 270, 330, 380, 685, 700, 900, 1100, 1200 or 1290) are very secure, alarms, intrusion control, random pathlength changes and the like can make undetected, unauthorized access to the system (30, 120, 130, 170, 190, 220, 250, 270, 330, 380, 685, 700, 900, 1100, 1200 or 1290) impossible with available interception techniques. |
