OPTICAL COMMUNICATION EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To realize communication with a satisfactory CN ratio even in long distance transmission by varying a resonance frequency in the optical transmission line of an optical external modulator from a resonance frequency in an optical fiber transmission line. SOLUTION: Since video signal light is transmitted with a frequency different from the frequency of phase noise occurring in the optical fiber transmission line 2 and by a frequency band resonating in the resonance frequency band of the optical external modulator 5, the video carrier frequency of a first TV modulator 11 (11a) from the transmission side of a system is set to 218MHz, for example. The video carrier frequency of a second TV modulator 11 (11b) is set to 401MHz, for example, so as to operate the optical external modulators 5 (5a and 5b). Thus, a noise floor can be reduced by about 10dB compared to a conventional system in which the acoustic frequency of the optical fiber transmission line 2 does not differ from that of the optical external modulator 5 so as to improve the CN ratio.