| 摘要 |
PURPOSE:To speed up the operation of an optical modulator by forming at least one layer of the layer which has the dielectric constant higher than the dielectric constant of air near a region where the light propagating in a light guide and the signal wave propagating in an electrode for modulation act on each other. CONSTITUTION:At least one layer of the layer 6 having the high dielectric constant is formed near the region where the modulating signal propagating in the electrodes 1 for modulation and the light propagating in the light guide 2 act on each other in such a manner that the propagation speeds of the signal waves propagating in the electrode for modulation and the light propagating in the light guide are approximated to each other. Since the layer 6 having the high dielectric constant exists near the progressive wave electrode, the effective dielectric constant epsiloneff for the modulating signal wave of the electrode 1 for modulation is increased. The higher effective refractive index nm to the modulating signal wave than with the optical modulator of the conventional constitution is thereby obtd. and, therefore, the difference in the phase speed between the modulating signal wave and the light is decreased and the high- speed operation is enabled. |
