| 摘要 |
PURPOSE:To obtain an optical waveguide which decreases the dependency of the loss on polarized light by subjecting the adjacent part along the curve part of the optical waveguide to an ion exchange from the surface of a substrate. CONSTITUTION:The Ti-diffused curve waveguide 2 and the ion exchange layer (proton exchange layer) 3 consisting of proton are formed on the substrate 1 consisting of a lithium niobate crystal (LiNbO3) having the Z-axis perpendicular to the substrate surface. Namely, the refractive index n0 to extraordinary light increases in the section subjected to the ion exchange in the case of the crystal, such as lithium niobate or lithium tantalate, having optical anisotropy. The confinement of light is, therefore, intensified in a TE mode and is weakened in a TM mode. The difference in the radiation loss between the TE mode and the TM mode is decreased. The dependency of the loss of the optical waveguide on the polarized light is decreased in this way. |
