LIGHT AMPLIFIER TYPE OPTICAL COMMUNICATION SYSTEM FOR CHANGING GAIN BY POLARIZATION OF INPUT SIGNAL

摘要

PROBLEM TO BE SOLVED: To simplify the interference of the polarization of transmitted optical signals by providing an optical fiber, upon receiving signals for modulating a light wave phase, having a sufficient polarization distribution function to polarization interference. SOLUTION: Polarized monochromatic light waves 10 from a laser transmitter 10 are inputted to an amplitude modulator 11 and control signals from a generator 13 for modulating the amplitude of the optical signals are received there. The signal output 14 of the amplitude modulator 11 is sent out through a long- distance optical fiber 15 to a reception equipment and a reception station 16. On the intermediate point of the optical fiber 15, repeaters 17 and 18 are provided for optical signal amplification and further, a polarization interference device 20 is provided so as to dissolve the polarization. The polarization interference device 20 has a lithium niobic acid crystal 25 and is provided with the optical fiber 22 for receiving signals from a modulator 21 for modulating the light wave phase provided with the sufficient polarization distribution function to the polarization interference. Thus, the execution of the polarization interference of the transmitted optical signals is simplified.