Waveguide type optical interference circuit

摘要

A waveguide-type optical interferometer includes at least one input waveguide (101, 102), an optical splitter (103) connected to the input waveguide (101, 102), at least one output waveguide, an optical combiner (106) connected to the output waveguide (104, 105), at least two arm waveguides (123a, 123b, 123c, 123d) that provide a connection between the optical splitter (103) and the optical combiner (106), and a half-wave plate (122) having an optic axis inclined at any one of 45° and -45° relative to optic axes of the at least two arm waveguides (123a, 123b, 123c, 123d). The waveguide-type optical interferometer further comprises phase difference providing waveguide portions (170) that provide a phase difference of 180° between polarizations crossing at right angles in the at least two arm waveguides (107, 108), at operating wavelengths used in the optical interferometer, the phase difference providing waveguide portions (170) being located either between the at least two arm waveguides (123a, 123b, 123c, 123d) and the optical splitter (103) or between the at least two arm waveguides (123a, 123b, 123c, 123d) and the optical combiner (106), wherein the half-wave plate (122) is located at a location corresponding to a midpoint of an optical path length of each of the at least two arm waveguides (123a, 123b, 123c, 123d).