| 摘要 |
PROBLEM TO BE SOLVED: To provide an operation point control method for a waveguide light modulator and the waveguide light modulator capable of performing precise operation point control, without elapsed deviation in an operation point and with a low production cost by a simple manufacturing process. SOLUTION: In the operation point control method of the waveguide light modulator provided with a substrate having an electrooptical effect, a Mach- Zehnder type optical waveguides 2a, 2b formed by doping and thermally diffusing the first substance on this substrate and modulating electrodes 3a, 3b, the second substance having a diffusion coefficient for the substrate larger than the first substance is doped in the vicinity of or just above of at least one side optical waveguide of the Mach-Zehnder type optical waveguides, and the operation point is coarsely adjusted, and only the second substance is thermally diffused 4, and the operation point is finely adjusted. Thus, the operation point of the waveguide light modulator is adjusted to a prescribed value. |
