| 摘要 |
PURPOSE:To obtain an optical switch whose switch voltage is comparatively low, and which can be formed easily, by allowing an optical axis of a crystal substrate provided with an optical directional coupler consisting of two pieces of optical waveguides being adjacent to each other, and a control electrode in the vicinity of the optical coupler, to coincide with the light transmission direction of the optical waveguide. CONSTITUTION:On a crystal substrate 11 having an optical anisotropy, an optical directional coupler 14 consisting of two pieces of optical waveguides 12, 13 being adjacent to each other, a control electrode 15 is provided in the vicinity of the optical directional coupler 14, and an optical axis Z of the crystal substrate 11 is allowed to coincide with the light transmission direction of the optical waveguides 12, 13. Accordingly, in moth TE and TM modes, an ordinary ray refractive index is related, therefore, waveguide characteristics coincide roughly, and the complete coupling width also becomes roughly equal. In such a way, a tapered structure becomes unnecessary, a switch voltage becomes smaller than that of a conventional tapered switch, and the optical switch can be formed easily. |
