| 摘要 |
PURPOSE:To obtain an optical waveguide by which the coupling efficiency of an optical fiber and an optical integrated circuit is good and a transmission loss by a bend, etc. of the waveguide is small, by providing a groove whose section is circular on a substrate, and packing this groove with an optical material whose refractive index is higher than that of the substrate. CONSTITUTION:When a tapered mask 3' is formed on a desired substrate 1 and etching is executed by making an argon ion incident vertically from the upper part, the substrate 1 and the mask 3' are etched by non-selectivity of etching. In this case, as for the end part of the mask 3', its dynamical strength is inferior to other part, therefore, it is etched quickly. Usually a substance whose etching rate is sufficiently smaller than the substrate 1 is used for the mask 3', and when etching is executed within the time when an interval L3 of the mask 3' is not varied, it is possible to dig a groove whose depth is D and whose section shape is semi-circular. In this case, thickness L1 of a non-tapered part of the mask 3' is reduced to thickness L1' by etching. In this regard, this semi- circular section structure can be changed by varying a taper angle psi of the mask 3' and a dispersion angle theta of an ion beam. |
