OUTPUT WAVEFORM STABILIZING METHOD FOR ELECTRIC FIELD ABSORPTION TYPE OPTICAL MODULATOR

摘要

PURPOSE:To hold the output waveform of an electric field absorption type optical modulator constant irrelevantly to temperature variation by detecting the mean level of the light output intensity of a light absorption part and controlling the wavelength of light from a laser light source so that the mean level becomes constant. CONSTITUTION:An optical current generated by the light absorption part 14 is led out as a voltage signal through a resistor 41 and this voltage signal is inputted to a comparator 42 together with a reference voltage signal from a reference voltage power source 44. Then a current source 46 is driven with the output of the comparator 42 to adjust the oscillation wavelength of the laser light source 16. Consequently, the wavelength of the light from the laser light source 16 is so controlled that the mean level of the light output intensity becomes constant. Consequently, the output waveform of the electric field absorption type optical modulator can be held constant irrelevantly to the temperature variation.