OPTICAL TRANSMITTER

摘要

PROBLEM TO BE SOLVED: To output a luminous signal with less distortion component by controlling the operating condition so as to minimize the magnitude of distortion in the luminous signal. SOLUTION: A multi-channel frequency multiplex signal given to a modulation signal input terminal 11 is superimposed with a bias current by an LD driving circuit 13 and converted into a modulation current to drive a semiconductor laser 12. A photoelectric converter 16 converts luminous signal from an optical demultiplexer 15 into an electric signal. A narrow band pass filter 17 extracts only the distortion component from the electric signal outputted from the photoelectric converter 16 and provides the output of the electric signal corresponding to the distortion component to a detection circuit 18. The detection circuit 18 detects the magnitude of the distortion from the electric signal of the distortion component outputted from the narrow band pass filter 17 and outputs a detection signal corresponding to the magnitude of distortion. A control circuit 19 controls the LD driving circuit 13 corresponding to the detection signal from the detection circuit 18 to output a DC bias current minimizing the distortion of the luminous signal outputted from an optical amplifier 14 by the LD driving circuit 13.