| 摘要 |
PURPOSE:To decrease the loss of a Y-shaped optical confluencing and multiplexing circuit by making the refractive index in the intersected part of an incident side optical waveguide larger than the refractive index in the peripheral part at the intersected part of the incident side optical waveguide and exit side optical waveguide. CONSTITUTION:An optical waveguide pattern of a Y shape is formed of a Ti film on an LiNbO3 substrate 201 and is diffused into the substrate 201, by which the refractive index of the part diffused with the Ti is increased and the incident side Ti-diffused waveguide 202, the refractive index region 203 of the intersected part and the exit side Ti-diffused waveguide 204 are formed. The refractive index difference between the optical waveguide and the LiNbO3 substrate 201 is proportional to the film thickness of the Ti film. The Y-shaped optical confluencing and multiplexing circuit having the high refractive index region 203 of a triangular shape at the intersected part is, therefore, constituted if the pattern having the large thickness of the Ti film is formed only in the triangular shaped part corresponding to the high refractive index region 203 of the intersected part and is thermally diffused into the LiNbO3 substrate 201. The loss of the Y-shaped optical confluencing and multiplexing circuit is thus decreased simply by adding the simple stage. |
