| 摘要 |
PURPOSE:To eliminate necessity of attenuating the light input level by a manual operation even in the case of using for a short distance such as a local station by expanding a dynamic range by raising a maximum light receiving level. CONSTITUTION:In a light receiver for amplifying to output a sending electric signal of a photodetector 1 for converting an optical input signal into an electric signal and variably regulating a bias voltage of the photodetector in response to a detected result of the amplitude of the output signal, a variable light attenuator 9 connected to be inserted to the midway of an input path of the input signal to the photodetector 1, and control means 6, 7, 8 for variably regulating the attenuation degree of the attenuator 9 in response to the detected result of the bias current to the photodetector 1, are provided. |
