| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to easily obtain an optical waveguide which is lessened in the propagation loss of guided light at a low temp. without causing the irregular reflection of the guided light at the side walls of a ridge structure by providing the side wall of at least the ridge structure with an inorg. thin film layer formed by using a sol-gel method. SOLUTION: The optical waveguide 190 having the ridge structure is provided with the ridge structure 118 on a substrate 110 and the inside of the ridge structure 118 is provided with the optical waveguide 114 of substantially a semicircular shape in section. The ridge structure 118 is successively provided with a lithium niobate thin film 130 and a buffer layer 120 across the upper flat part 110a of the substrate 110 at its both skirts. Namely, the optical waveguide 190 is provided with the lithium niobate thin film 130 as the inorg. thin-film layer formed by using the sol-gel method on the side wall 118a of the ridge structure. Then, even if the side wall 118a of the ridge structure is roughened right after etching, the extremely smooth side wall is obtd. by the lithium niobate thin film 130. |
