| 摘要 |
PROBLEM TO BE SOLVED: To provide a plane type optical waveguide of which bending loss is effectively reduced without increasing the coupling loss to fibers, the waveguide loss by boundary roughening, polarization dependence, etc., and a process for producing the same. SOLUTION: A lower clad layer 2 is formed on a silicon substrate 1 and core layers 3 are patterned and formed thereon. The core layers 3 have straight parts 3a, 3b and bent part 3c. Upper clad layers consist of first upper clad layers 4a, 4b covering the straight parts 3a, 3b of the core layers 3 and a second upper clad layer 5 covering the bent part 3c. The second upper clad layer 5 is made low in refractive index as compared with that of the first upper clad layers 4a, 4b, thereby, the refractive index difference from the core layers 3 is increased and the bending loss is reduced. |
