| 摘要 |
PURPOSE:To prevent irregular strain from being applied to an optical waveguide which is formed on the surface of a ferroelectric crystal substrate by forming the same dielectric film with a buffer layer even on the reverse surface of the ferro-electric crystal substrate under the same conditions as the buffer layers. CONSTITUTION:On the surface of the lithium niobate crystal substrate 10, titanium (Ti) is diffused at 900 - 1,100 deg.C for several hours to form optical waveguides 11 and 12 which are about 3 - 10 mum deep, and both the optical waveguides 11 and 12 are put close to several mum at the center part of the substrate 10 to constitute a directional coupler 13. On the optical waveguides 11 and 12, electrodes 15 are formed across the buffer layer 13 so as to prevent light absorption by the electrodes. On the reverse surface of the substrate 10, on the other hand, the same dielectric film 16 with the buffer layer 14 is formed under the same conditions as the buffer layer 14. |
