Patent ID: 7720384

Claim:
A wavelength division multiplexing apparatus, comprising: a transponder unit; and a wavelength division multiplexing unit to be connected with the transponder unit, wherein the wavelength division multiplexing unit multiplexes in wavelength a plurality of lights having different wavelengths which are received from the transponder unit to send the wavelength-multiplexed lights, when receiving wavelength-multiplexed lights, divides the received wavelength-multiplexed lights into lights having different wavelengths, to transmit the divided lights to the transponder unit, wherein the transponder unit includes a plurality of transponders that are prepared in each wavelength of the plurality of lights which are multiplexed and divided by the wavelength division multiplexing unit, and each transponder transmits and receives one of the plurality of lights with respect to the wavelength division multiplexing unit, and wherein at least one of the plurality of transponders comprises: a detection unit to detect the wavelength of the received light having one of the different wavelengths which is received from the wavelength division multiplexing unit when the one transponder is connected to the wavelength division multiplexing unit; a determination unit to determine a transmission wavelength which is a wavelength of the light transmitted to the wavelength division multiplexing unit as the same wavelength with the wavelength of the received light which is detected by the detection unit; and a setting control unit to perform setting to convert the wavelength of the light to be transmitted to the wavelength division multiplexing unit into the transmission wavelength for transmission.