| 摘要 |
PURPOSE:To enhance the coupling efficiency to an optical fiber and to decrease a coupling loss by sticking a material which lowers the refractive index to the peripheral part of the part where a material to increase the refractive index is adhered and diffusing the materials into a waveguide substrate, thereby forming the spot shape of the waveguide layer to an approximately round shape. CONSTITUTION:The material 12 to lower the refractive index is stuck to the peripheral part of the part of the light guide where the material 11 to increase the refractive index is adhered. These materials are diffused into the waveguide substrate 10 to diffuse the material 12 to lower the refractive index partially into the part where the refractive index is increased by the diffusion of the material 11 to increase the refractive index. The spot shape of the waveguide 13 having the refractive index to the waveguide substrate 10 is, therefore, made into the approximately circular shape. The mode with the optical fiber having the circular spot shape is matched in this way, by which the coupling loss is decreased and the excellent coupling property is obtd. |
