| 摘要 |
PURPOSE:To prevent ions from migrating in a buffer layer when switching operation for applying a DC electric field is performed by providing the buffer layer between an optical waveguide and electrodes, and using a silicone nitride film as the buffer layer. CONSTITUTION:The buffer layer 13 is provided between the optical waveguide 12 and electrodes 14 and 15 and the silicon nitride film is used as the buffer layer 13. Namely, the silicon nitride film as the buffer layer 13 is free from an oxygen defect which is generated when an oxide such as a SiO2 film and an Al2O3 film is formed by sputtering or vapor deposition and the density of the formed film is high. Consequently, the mixture of ions in the buffer layer is small, ions are hard to migrate at the time of applying electric field, and a DC drift can be evaded sufficiently by the film formed by sputtering. |
