| 摘要 |
PURPOSE:To realize the device which obtains a desired optical coupling state at high yield by forming unevenness at a specific interval on a buffer layer, which covers optical waveguides on a dielectric crystal substrate, nearby control electrodes. CONSTITUTION:On the buffer layer 6 nearby the control electrode 5, uneven parts 10 which intersect one another periodically are formed. A change in the coupling state of a directional coupler 4 which is generated after the formation of the control electrode 5 can be suppressed. Namely, strain generated in the dielectric crystal substrate 1 when a control electrode film and a buffer layer film are deposited is dispersed by forming the buffer layer in an elastic discontinuous area similar to the control electrode part 5 although the strain is concentrated nearby the control electrode 5 after the formation of the control electrode. Therefore optical waveguide characteristics when optical waveguides 2 and 3 are formed on the substrate 1 are maintained and the coupling state of the directional coupler 4 does not change at all. |
