OPTICAL HOMODYNE DETECTION COMMUNICATION SYSTEM AND EQUIPMENT, AND SYSTEM AND EQUIPMENT FOR OPTICAL CODE DIVISION MULTIPLEX TRANSMISSION USING SAME

摘要

PROBLEM TO BE SOLVED: To make a frequency of a conventional homodyne communication system stable in which an optical frequency converter is used to recover a reception signal as a local oscillating light with a different frequency and to detect the signal. SOLUTION: An optical coder 10 generates an optical pulse of an orthogonal code from a beam of a laser 1 on the transmitter side and an optical amplitude modulator 2 applies optical amplitude modulation to the generated light by information bits. Then an output of an optical local oscillator 5 having a frequency different from the frequency of the laser 1 is branched into two to conduct optical homodyne detection on the receiver side, a frequency converter 6 is used to recover information of the received signal with one local oscillation light, the recovered information is synthesized with the other local oscillation light at a 3dB coupler 8, a balanced photoelectric converter 9 conducts inverse spread and photoelectric conversion and an optical current is integrated by an integration device 13 and discriminated by a peak discrimination device 14 to detect the transmission information.