Patent ID: 8244133

Claim:
An optical waveband demultiplexer operable to separate a wavelength-division multiplexed light beam consisting of a plurality of wavebands each including a plurality of optical channels, into a predetermined plurality of wavebands, and to output the separated plurality of wavebands from a plurality of output ports, respectively, said optical waveband demultiplexer comprising: a first array waveguide grating through which said wavelength-division multiplexed light beam is transmitted and which is capable of performing demultiplexing and multiplexing functions with a resolution corresponding to wavelengths of said optical channels, said first array waveguide grating having a characteristic of sequentially shifting its output ports by one position with shifting of its input ports by one position, and a characteristic of outputting signals of the plurality of optical channels transmitted through one fiber connected to each of the input ports such that the signals are outputted from the respective different output ports; and a second array waveguide grating through which said wavelength-division multiplexed light beam is then transmitted and which is capable of performing demultiplexing and multiplexing functions with a resolution corresponding to the wavelengths of said optical channels, said second array waveguide grating having a characteristic of sequentially shifting its output ports by one position with shifting of its input ports by one position, whereby said wavelength-division multiplexed light beam incident upon predetermined ones of the input ports of said first array waveguide grating is separated into a plurality of wavebands each including the mutually different optical channels which are selected from the optical channels included in the wavelength-division multiplexed light beam incident upon the predetermined input ports and which are different from the optical channels incident upon the other input ports, and the separated plurality of wavebands are respectively outputted concurrently from the plurality of output ports of said second array waveguide grating.