| 摘要 |
PURPOSE:To reduce the coupling between two waveguides except at an intersection part where two waveguides which differ in refractive index cross each other by setting the refractive index of the intersection part equal to or larger than the refractive index of the waveguide having the higher refractive index. CONSTITUTION:The waveguide 14 which has the higher refractive index and the waveguide 15 with a lower refractive index are formed on a substrate 1 while crossing each other at the intersection point 3. Then, the waveguide 14 has confinement structure at an intersection part 2 formed about the intersection point 3 and the waveguide 15 has no confinement structure. Consequently, the coupling between the waveguides 14 and 15 is reducible except at the intersection part 2. Waveguide light 16 to the waveguide 14 travels at the intersection part 2 almost without being diffracted and waveguide light 17 to the waveguide 15 is bent away from the waveguide 14 like light 18, so the leak-in rate of the light 18 decreases. Thus, crosstalk is reduced. |
