Patent ID: 7139451

Claim:
An optical communication system comprising: optical transmitting means for transmitting optical signals of respective wavelengths parallel to each other; a multiplexer for wavelength-division multiplexing the optical signals of respective wavelengths transmitted by said optical transmitting means; an optical transmission path for transmitting a wavelength-division multiplexed optical signal output from said multiplexer; a node disposed in said optical transmission path and having an arrayed waveguide grating; a demultiplexer for being supplied with the optical signal transmitted over said optical transmission path via said node and demultiplexing the optical signal into the optical signals of respective wavelengths; and optical receiving means for receiving the optical signals of respective wavelengths demultiplexed by said demultiplexer, wherein said multiplexer comprises an arrayed waveguide grating comprising: a plurality of input waveguides for inputting signal lights having different wavelengths from a light source; one or plural output waveguides for outputting signal lights; a channel waveguide array having waveguides which are successively longer with predetermined waveguide length differences; an output slab waveguide connecting an output end of said channel waveguide array to said output waveguides; and an input slab waveguide connecting an input end of said channel waveguide array to said input waveguides, and having optical input/output characteristics set to predetermined ratios for the respective input waveguides with respect to the output waveguides, wherein said output waveguides are configured such that an output level of said signal lights is adjusted in the arrayed waveguide grating of said multiplexer, wherein said demultiplexer comprises an arrayed waveguide grating comprising: one or plural input waveguides for inputting signal lights; a plurality of output waveguides for outputting signal lights; a channel waveguide array having waveguides which are successively longer with predetermined waveguide length differences; an input slab waveguide connecting an input end of said channel waveguide array to said input waveguides; and an output slab waveguide connecting an output end of said channel waveguide array to said output waveguides, and having optical input/output characteristics set to predetermined ratios for the respective output waveguides with respect to said input waveguides, wherein said output waveguides are configured such that an output level of said signal lights is adjusted in the arrayed waveguide grating of said demultiplexer, and wherein a central axis of at least one of said output waveguides are out of alignment with a remainder of said output waveguides.