SINGLEEMODE FIBER OPTICAL COMMUNICATION SYSTEM

摘要

PURPOSE:To realize a communication system having the margin to the noise for the optical communication system using the single-mode optical fiber, by carrying out the optical phase modulation at the transmitter side and the differential synchronous phase detection at the receiver side respectively. CONSTITUTION:The light given from coherent light source 14 is led to external modulator 16 to undergo the phase modulation by the electric signal sent from transmitter 18. The light emitted from transmitting part 11 reaches receiving part 13 via single-mode optical fiber 20. The light is branched off at part 13 through optical branching circuit 22 and then led to input terminal 25a and 25b of optical hybrid circuit 25 via two optical waveguides 23 and 24 featuring different delay time. The light of two output terminals 25c 25d for the in-phase component and the reverse-phase component is converted into the electric signal to be led to receiver 29 after amplification through differential amplifier 28.