| 摘要 |
PURPOSE:To obtain the uniform characterisics with high accuracy for an optical waveguide, by irradiating a laser beam to the waveguide and controlling the distribution of refractive index with the local heating of the waveguide. CONSTITUTION:An optical waveguide is formed by diffusing Ti to a substrate 1 of an LiNbO3 single crystal. The light of the He-Ne laser 2 is irradiated to the optical waveguide, and the two output beams are received by a silicon photodiode 3. Then powers P1 and P2 of both beams are measured, and at the same time the beam of a CO2 laser 5 is irradiated at the peak position A of the refractive index at the incident edge side of the optical waveguide. As the time of irradiation elapses, the curve of the refractive index is gradually flattened. Then a light beam 7 in the waveguide moves gradually toward the route shown by a dotted line, and accordingly the branching ratio P1/(P1+P2) is reduced to be set at a prescribed level. In the same way, the laser beam 5 is irradiated at the maximum point B of the refractive index at the output edge of the waveguide. Thus the control is possible for the distribution of the refractive index. In such way, the characteristics of an optical waveguide are made uniform with high accuracy. |
