Patent ID: 7130504

Claim:
An optical demultiplexing device that splits a wavelength division multiplexing (WDM) signal into a plurality of channel signals of an identical diffraction order, comprising: a first output port set that includes a first output port and a second output port to each of which one of the channel signals is input so that a wavelength shift of the channel signal from a center wavelength of the first output port set is calculated based on an intensity ratio of an optical signal output from the first output port and an optical signal output from the second output port; and a second output port set that includes a third output port and a fourth output port to each of which another one of the channel signals is input so that a wavelength shift of the another channel signal from a center wavelength of the second output port set is calculated based on an intensity ratio of an optical signal output from the third output port and an optical signal output from the fourth output port, wherein: the second output port set is adjacent to the first output port set, the third output port is adjacent to the second output port, and optical crosstalk between the first output port and the second output port and optical crosstalk between the third output port and the fourth output port are larger than optical crosstalk between the second output port and the third output port.