| 摘要 |
PROBLEM TO BE SOLVED: To easily form a refractive index distribution in core and clad layers near the light input or output end of a waveguide and to enhance the control precision of the refractive index distribution by forming a low refractive index core layer region near the light input or output end of the waveguide. SOLUTION: A lower clad layer 2 having a low refractive index nb is formed on a substrate 1 and a polymer layer (a core layer 3 and lateral clad layers 4-1, 4-2) for photo-bleaching is formed on the lower clad layer 2. The refractive index nW of the core layer 3 is higher than the refractive index ns of the lower clad layer 2 and also higher than the refractive index ns of the lateral clad layers 4-1, 4-2. The refractive index ns of the lateral clad layers 4-1, 4-2 is equal to or slightly lower or higher than the refractive index nb. An upper clad layer 5 having a refractive index nc (nc<nw) is formed on the polymer layer and the top of the clad layer 5 is coated with a UV reflecting layer (or absorbing layer) 6. The refractive index of the core layer near the light input or output end of the resulting waveguide is lowered and a low refractive index core layer region is formed. |
