| 摘要 |
PURPOSE:To reduce coupling loss when coupling with an optical fiber, etc., by performing diffusion so that the maximum distribution of Ti can be obtained in the deepest area of a substrate. CONSTITUTION:An area in which the highest density of a metallic element can be obtained within a plane in parallel with the surface of the substrate 1 is set so that it can exist in the inside than the surface of the substrate 1. For example, after a Ti layer is diffused in the substrate 1, and an optical waveguide 40 is formed, the substrate 1 is further sandwiched between Pt plates 12a and 12b, and rediffusion for six hours is performed as applying a voltage of 500V to the Pt plates 12a, 12b in a furnace of 950 deg.C, and it is diffused in the inside of the substrate. In other words, the diffusion speed of the metallic element can be increased in the applying direction of an electric field by applying the diffusion of the metallic element in the electric field, which enables the metallic element to be diffused in the depth direction of the substrate 1. Thereby, it follows that the peak of the distribution of a refractive index can be positioned at the inside of the substrate, and it resembles the waveguide mode of the optical fiber, etc., therefore, the coupling loss when coupling them can be reduced. |
