Patent ID: 6934428

Claim:
A variable optical attenuator comprising: an input waveguide which increases in width along an optical path in order to expand the width of light entering through an optical fiber of an input end of the input waveguide; an output waveguide which faces and is separated from the input waveguide by a certain gap and decreases in width along the optical path in order to make the expanded light converge towards an optical fiber of an output end; an optical shutter which moves in the space between the input waveguide and the output waveguide and variably attenuates the amount of the light; an MEMS (micro-electrical-mechanical system) actuator which moves the optical shutter; and a controller which controls the MEMS actuator, wherein a waveguide for control branched off from the output waveguide is adjacent to the output end of the output waveguide, and a photodetector is in front of the output end of the waveguide for control, the controller controls the MEMS actuator depending on the intensity of the light sensed by the photodetector and adjusts the position of the optical shutter.