| 摘要 |
PURPOSE:To keep an operating voltage low and to improve optical coupling efficiency by providing a switch part having high refractive index only to the surface of an optical waveguide and providing optical fiber coupling parts having a symmetrical refractive index distribution to both sides thereof. CONSTITUTION:The optical waveguide 5 is formed of the optical switch part 6 and the optical fiber coupling parts 7 on both sides thereof. Mg is first diffused in an LiNbO3 substrate to form the optical switch part 6 at the time of forming such waveguide. Ti is then diffused to the part of the substrate 1 corresponding to the waveguide pattern passing the optical switch part 6 to form the optical waveguide 5. Mg is diffused in both ends thereof to form the optical fiber coupling parts 7. Since the switch part 6 has the high refractive index only on the surface, the operating voltage is kept low. The optical fiber coupling parts 7 have the symmetrical refractive index distributions and can, therefore, improve the coupling efficiency to optical fibers. |
