OPTICAL LEVEL ADJUSTING CIRCUIT

摘要

PURPOSE:To quickly set the reception level of an optical receiver and the transmission level of an optical transmitter to optimum levels. CONSTITUTION:The optical level adjusting circuit which detects the level of the optical signal passing an optical variable attenuator 11 by a photodetector 12 and adjusts the extent of attenuation of the optical variable attenuator 11 in accordance with the output level of the photodetector 12 is characterized by using a field absorption type modulator as the photodetector 12 and using the DC, which flows in accordance with the DC voltage applied to this field absorption type modulator and the optical level, for adjustment of the extent of attenuation of the optical variable attenuator 11 and adjusting the optical output transmitted through the field absorption type modulator into a certain value and is characterized by providing the means which uses the DC of the photodetector 12 to read the optical output level of the photodetector 12.