Patent ID: 7190855

Claim:
A dual-band wavelength division multiplexer including a first and a second slab waveguide, a plurality of channel waveguides connecting the first slab waveguide to the second slab waveguide, an input part connected to the first slab waveguide, and an output part connected to the second slab waveguide, wherein the input part comprising: an input waveguide configured to receive an optical signal; a wavelength division multiplexing filter connected to the input waveguide, arranged to output an optical signal in a first band to a first connecting waveguide, and output an optical signal in a second band to a second connecting waveguide; a first mode converter connected to the wavelength division multiplexing filter through the first connecting waveguide and arranged to mode-convert the input optical signal in the first band; and a second mode converter connected to the wavelength division multiplexing filter through the second connecting waveguide and arranged to mode-convert the input optical signal in the second band, wherein the first mode converter is configured to receive the first band with center wavelength shorter than the center wavelength of the second band and wherein the output mode of the first mode converter has a width larger than that of the output mode of the second mode converter, and wherein the first mode converter is configured to output an output mode having a width different from that of an output mode output from the second mode converter.