| 摘要 |
PURPOSE:To reduce coupling length and to reduce the size of the optical switch by increasing the film thickness of a coupling part when the rib width, rib interval, etc., are equal to those of conventional constitution. CONSTITUTION:A lower clad layer 12 and an optical guide layer 14 are provided on a substrate 10 in order, two upper clad layers 16a and 16b are formed on the optical guide layer 14, and the coupling part 28 which couples the upper clad layers 16a and 16b is formed. Thus, a clad layer as the coupling part 28 which is thinner than the upper clad layers 16a and 16b is provided between the upper clad layers 16a and 16b, therefore, between 1st and 2nd ribs 24a and 24b, so electric field coupling is increased between the 1st and 2nd ribs 24a and 24b. Then the electric field coupling between the 1st and 2nd ribs 24a and 24b is increased by increasing the film thickness (h) of the coupling part 28. Consequently, the coupling length Lc is increases and the optical switch which is smaller than a conventional optical switch is obtained. |
