Optical waveguide circuit

摘要

An optical waveguide circuit capable of controlling polarization crosstalk is provided. An under cladding is formed on a silicon substrate (11). A core is formed on the under cladding and has a waveguide structure in which one or more optical input waveguides (12) arranged side by side are connected at their exit ends with a first slab guide (13), which is connected at its exit end with an arrayed waveguide (14) composed of plural channel waveguides (14a) that are different in length with the difference preset, and the arrayed waveguide (14) is connected at its exit end with a second slab waveguide (15), which is connected at its exit end with a plurality of optical output waveguides (16). The top of the core is covered with an over cladding to form an optical waveguide portion (10) composed of the under and over claddings and the core. A plurality of light beams having different wavelengths are entered to the core in the multiplexed manner, and the entered light beams are outputted separately on the basis of the wavelength. The claddings and the core are formed from silica glass. The birefringence B in the optical waveguide portion (10) is set so as to satisfy |B|>=1.2x10-4 to reduce polarization crosstalk to -20 dB or less.