| 摘要 |
PURPOSE:To widen a modulation band by using a simple manufacturing process by forming a groove in a substrate below electrodes. CONSTITUTION:When the groove 11b is formed in the substrate 11, the thickness of the substrate (large refractive index) 11 under the electrodes 3a and 3b is smaller by the thickness of the groove 11b and an air layer (small refractive index) is formed by the thickness. Then the effective refractive index of a microwave decreases corresponding to the groove (air layer) 11b and approximates the refractive index of a light wave. The speed difference between the light wave and microwave becomes extremely small, so the modulation speed can be increased and the modulation band can be widened. When the groove 1b is formed reaching the bottom surface of the substrate 11, this effect increases more. Further, the groove 11b is easily formed by using a cutting saw, so the manufacturing process is extremely simple. |
