OPTICAL WAVEGUIDE CIRCUIT

摘要

An optical waveguide circuit such as an array waveguide diffraction grating in which the influence of polarization-dependent loss can be suppressed without providing a half-wave plate. A lower clad is formed on a silicon wafer (11). A core having the following waveguide constitution is formed thereon. An input-side slab waveguide (13) is connected to the output side of a plurality of incidence waveguides (12), and a plurality of array waveguides (14) having different lengths are connected side by side to the output side. An output-side slab waveguide (15) is connected to the output side thereof, and a plurality of output waveguides (16) is connected to the output side. The core is clad with upper clad. A plurality of multiplex-inputted incident light beams having different wavelengths are separated for every wavelength and outputted. The clad and the core are made of silica glass. The absolute value |B| of double refraction caused in the optical waveguide circuit is |B| ≤ 5.34 x 10-5. The relationship between the coefficient of thermal expansion αg of the upper clad and the coefficient of thermal expansion αs of the silicon wafer is expressed by αs-2.0 x 10-7≤αs 2.0 x 10-7.