| 摘要 |
PURPOSE:To lessen the loss of the light propagating in optical waveguide by making the spacings between electrode and the optical waveguide larger toward both ends of the electrode than the intermediate part of the electrode. CONSTITUTION:A substrate 1 is provided with a buffer layer 5 on the optical waveguides 2. The electrodes 6 are respectively arranged in the parts of two optical waveguides 2 branched. A buffer layer 5 is provided with tapered part 8 in this branching type optical modulator. The spacings between the electrodes 6 formed on the buffer layer 5 and the optical waveguides 2 are, therefore, made gradually larger toward the end parts E than the intermediate parts F of the electrodes 6 and the intensity of the electric fields applied on the optical waveguides 2 from the electrodes 6 is made gradually smaller as the distances between the electrodes 6 and the optical waveguides 2 increase gradually. Then, the refractive index distribution of the optical waveguides 2 is eventually continuously changed and the continuous changing of the amplitude distribution of the light propagating in the optical waveguides 2 is resulted. The light radiating from the optical waveguides 2 is consequently decreased in the parts E at the ends of the electrodes. |
