| 摘要 |
PROBLEM TO BE SOLVED: To obtain a channel-shaped optical waveguide giving a satisfactory near field image close to a perfect circle in the case of not only a Z-cut substrate but also a Y-cut substrate by thermally diffusing a zinc oxide in a ferroelectric substrate. SOLUTION: This waveguide type element contains a channel-shaped optical waveguide formed by thermally diffusing zinc oxide in a ferroelectric substrate. Since zinc oxide is used as a diffusible material forming the optical waveguide, the optical waveguide is formed as a single-mode channel-shaped optical waveguide having a distribution of the intensity of emergent light (near field image) equivalent or close to a perfect circle, that is, having as aspect ratio of about 0.8-1.5. Suitability to coupling with an optical fiber is improved and insertion loss due to connection is reduced. Lithium niobate (LiNbO3 ) or lithium tantalate (LiTaO3 ) may be used as the ferroelectric and lithium niobate is preferably used. |
