| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical waveguide which is capable of suppressing the coupling and reverse traveling of the reflected return light generated at a joint surface between a light input part and a light exit part to the core in the light input part when the light propagates from the light input part to the light exit part. SOLUTION: This optical waveguide is joined with a first core 3 constituting the light input part 1 and a second core 4 constituting the light output part 11. The second core 4 varies in at least either of the material or composition from the first core 3. The refractive index of the second core 4 is made lower than the refractive index of the first core 3. The optical waveguide described above is so formed that at least either of the thickness D and width W of the second core 4 is larger than that of the first core 3. The joint surfaces of the first core 3 and the second core 4 may be made diagonal with the progressing direction of the light at this time. These points are applicable similarly to the case the light propagates conversely from the second core 4 to the first core 3, i.e., the case 11 is formed as the light input part and 1 as the light output part. |
