OPTICAL WAVEGUIDE ELEMENT AND PHASE CONTROL METHOD FOR OPTICAL WAVEGUIDE ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide a new optical waveguide type element which permits ON/OFF control over an external signal at a high quenching ratio by compensating effective refractive index variation of a substrate and an optical waveguide due to defects and stress generated at the time of the production and a phase control method for the optical waveguide element. SOLUTION: This invented optical waveguide element 10 has a substrate 1 having electrooptic effect, a Mach-Zehnder type optical waveguide 2 for guiding a light wave, and a signal electrode 4 and ground electrodes 5-1 and 5-2 for controlling the light wave guided in the optical waveguide 2. At least part of 1st and 2nd branch optical waveguides 3-1 and 3-2 constituting the optical waveguide 2 on the substrate, a film body 6 of a material having a higher effective refractive index than the optical waveguide is formed to thickness less than a quarter as large as the wavelength of the light wave. Here, the film body 6 is formed by forming a specific thin film and then trimming the thin film so that phase control is placed in the best state.