Patent ID: 7280713

Claim:
An optical waveguide device, comprising: a substrate having an electro-optical effect; a polarization wave separating waveguide formed on said substrate for separating propagation light into polarization waves of polarization modes of TM and TE; two linear waveguides formed on said substrate for individually propagating the propagation lights separated by said polarization wave separating waveguide; and a polarization wave synthesis waveguide formed on said substrate for synthesizing the propagation lights from said two linear waveguides; said polarization wave separating waveguide including two input waveguides, a waveguide coupling element for coupling said two input waveguides with a distance d 1 , and two output waveguides branched from said waveguide coupling element with another distance d 2 ; the distance d 1 in said waveguide coupling element being set to less than one half of width w 01 at a portion at which each of said input waveguides is connected to said waveguide coupling element; width w w1 of said waveguide coupling element on said input waveguides side being set to 2.5 times to 3.5 times the width w 01 ; the length of said waveguide coupling element being set so that, where polarization waves of the two polarization modes of TM and TE are inputted from one of said two input waveguides, the polarization waves may individually be outputted to different ones of said output waveguides from each other.