OPTICAL FIBER COMMUNICATION SYSTEM HAVING CONFIDENTIALITY

PROBLEM TO BE SOLVED: To provide an optical fiber communication system allowed to be easily applied to an existing optical communication system and capable of securing confidentiality so that a secret communication signal is not detected even when a light wavelength is analyzed.SOLUTION: When transmitting signals to respective optical fiber lines 5a, 5a', light intensity modulation is respectively performed by communication signal/light modulators 22a, 32a by inputting a communication signal Sa1 outputted from a transmitter Tx1 or a communication signal Sa2 outputted from a transmitter Tx2 to light to be an optical carrier wave emitted from light sources 21, 31 as input information, light intensity modulation is respectively performed by dummy signal/light modulators 22b, 32b by inputting a dummy signal Sd as input information, and wavelength dispersion by first transmission side wavelength dispersion controllers 23a, 33a is respectively added between the light intensity modulation by the communication signal/light modulators 22a, 32a and the light intensity modulation by the dummy signal/light modulators 22b, 32b.