VARIABLE-WAVELENGTH FILTER DEVICE AND ITS OPERATING METHOD

摘要

PURPOSE:To provide a variable-wavelength filter device wherein a wavelength can be detected and tuned without branching an optical signal and the number of constituent components for a receiver is not increased even when a wavelength multiplexing becomes large and to provide an optical communication system which includes it. CONSTITUTION:A variable-wavelength filter device is constituted of the following: a variable-wavelength bandpass filter 1 which can change a transmitted wavelength by control from the outside; a light amplifier 2 in which a voltage change is caused between terminals when light is being amplified; and a control circuit 3 which performs a control operation so as to change the transmitted wavelength of the variable-wavelength filter 1 according to the voltage change. By this constitution, an optical signal at a desired wavelength can be selected and detected without branching the optical signal.