OPTICAL WAVELENGTH MULTIPLEXER/DEMULTIPLEXER

PROBLEM TO BE SOLVED: To provide the optical wavelength multiplexer/demultipiexer wherein loss variations to wavelength variations of a light source are small and moreover stable multiplexing/demultiplexing of optical signals are possible. SOLUTION: An array waveguide diffraction grating 106, a sectorial inputting side slab waveguide 104 connecting an inputting channel waveguide 102 to the array waveguide diffraction grating 106, and a sectorial outputting side slab waveguide 107 connecting an outputting channel waveguide 108 to the array waveguide diffraction grating 106 are provided. The interval between the central axis of respective channel waveguides 105 constituting the array waveguide diffraction grating 106 and the central axis of respective adjacent channel waveguides 105 is gradually varied over the whole channel waveguides 105 in at least one side of the connecting part between the inputting side slab waveguide 104 and the array waveguide diffraction grating 106 or the connecting part between the outputting side slab waveguide 107 and the array waveguide diffraction grating 106.