Patent ID: 6947631

Claim:
A waveguide-type optical multiplexer/demultiplexer provided with Mach-Zehnder interference circuits connected in multistage, comprising: first; second and third optical multiplexer/demultiplexer circuits, wherein said each optical multiplexer/demultiplexer circuit comprises first to fourth input-output ports that are operable to input wavelength division multiplex signals having predetermined wavelength spacing and wavelength λ 1 , λ 2 , λ 3 , λ 4 , λ 5 , λ 6 . . . through said first input-output port and to output multiplex signals of odd wavelength λ 1 , λ 3 , λ 5 . . . from said third input-output port and multiplex signals of even wavelength λ 2 , λ 4 , λ 6 . . . from said fourth input-output port, and to input said wavelength division multiplex signals of wavelength λ 1 , λ 2 , λ 3 , λ 4 , λ 5 , λ 6 . . . through a second input-output port and to output multiplex signals of odd wavelength λ 1 , λ 3 , λ 5 . . . from said fourth input-output port and multiplex signals of even wavelength λ 2 , λ 4 , λ 6 . . . from said third input-output port, wherein said third input-output port of said first optical multiplexer/demultiplexer circuit is connected to said third input-output port of said second optical multiplexer/demultiplexer circuit, and said fourth input-output port of said first optical multiplexer/demultiplexer circuit is connected to said fourth input-output port of said third optical multiplexer/demultiplexer circuit, and wherein said wavelength division multiplex signals having wavelength λ 1 , λ 2 , λ 3 , λ 4 , λ 5 , λ 6 . . . are input through said first input-output port of said first optical multiplexer/demultiplexer circuit, multiplex signals of odd wavelength λ 1 , λ 3 , λ 5 . . . are output from said first input-output port of said second optical multiplexer/demultiplexer circuit, and multiplex signals of even wavelength λ 2 , λ 4 , λ 6 . . . are output from said first input-output port of said third optical multiplexer/demultiplexer circuit.