WAVEGUIDE OPTICAL INTERFEROMETER

摘要

A waveguide optical interferometer which is free from an additional work and excessive loss of light which accompanies the insertion of a 1/2 wavelength plate, low in cost, has high reliability and is independent of polarization. In an optical multiplexer / demultiplexer such as an AWG, a Mach-Zehnder interferometer which utilizes interference of light beam passing through a plurality of optical waveguides of different lengths, all the integrals of the birefringence values of the optical waveguides (which may change or not change along the waveguides) in the longitudinal direction of the waveguides (201 and 202) are made to be equal to each other. Thus, polarization-independent operation can be realized and, to the contrary, a polarized beam splitter can be realized only by changing the waveguide widths. For instance, the core width averaged in the longitudinal directions of short optical waveguides out of the optical waveguides having different lengths is made wide, and the averaged core width of long optical waveguides is made narrow, thereby realizing polization independence. <IMAGE>