OPTICAL SIGNAL TRANSMISSION METHOD

摘要

PURPOSE:To prevent the deterioration in a video image by superimposing a modulation signal light from a stimulated laser depending on a detected signal component onto a signal light from a laser diode so as to decrease the distortion signal component of a base band. CONSTITUTION:A monitor PD (photo diode) 13 monitors the signal light of an output waveform from an optical amplifier 12 and outputs a photoelectric- converted signal to a control circuit 14. The circuit 14 adjusts the frequency band of the input signal to a base band and detects the distortion signal component of the same frequency as the frequency of a video period signal included in the signal. An oscillator 15 adds a modulation signal to a excited laser 16 by direct luminance modulation based on the control of the circuit 14 and the laser 16 outputs the modulation signal light subjected to electrooptic conversion to the optical amplifier 12 based on the modulation signal from the oscillator 15 and superimposes the signal onto a signal light from the laser diode 11. Thus, the signal level of the distortion signal component of a base band is decreased and the signal light without the distortion signal component is outputted.