Patent ID: 8200053

Claim:
An optical apparatus, comprising: a plurality of input ports, each of which receive a wavelength division multiplexed (WDM) light as an input; an output port; a first wavelength dividing unit that divides lights from the plurality of input ports into divided lights with different wavelengths; an optical signal processing unit that reflects the divided lights respectively to the first wavelength dividing unit, and directs light from one of the plurality of input ports to the output port for a respective wavelength of the divided lights; a light source that outputs monitor lights that have wavelengths equal to the different wavelengths/N, where N is 2 or more integers; a first coupler that branches a monitor light into a plurality of monitor lights and outputs the plurality of monitor lights to the plurality of input ports; a second coupler that branches the monitor lights from the output port and outputs the branched output monitor light; a second wavelength dividing unit that divides the branched monitoring lights into divided lights with different wavelengths; and a monitoring unit that monitors the divided lights from the second wavelength dividing unit, and where the optical signal processing unit is monitored based on a monitor result.