| 摘要 |
PURPOSE:To make the refractive index in a crossed part uniform and to decrease crosstalk in the stage of diffusing a material such as metal in a substrate and forming a crossed type optical waveguide by controlling the layer thckness of the diffusive material to be deposited in the region to be formed with the crossed part. CONSTITUTION:Two slender layers 2 consisting of a diffusive material such as metallic titanium or the like are deposited so as to cross each other on the surface of a substrate 1 consisting of a crystal of LiNbO3 or the like. The layer thickness of the diffusive material to be deposited on the crossed part in this stage is made as large about 770Angstrom in shaded regions 7 and all the layer thicknesses of the diffusive material are made uniform and as thin as about 520Angstrom in the parts 71 except the regions 7. The substrate is then heat-treated to about 1,040 deg.C to diffuse the material 2 into the substrate 1, whereby the optical waveguides 3 having the refractive index higher than the refractive index of the substrate 1 are formed. The waveguides 3 obtd. by the above-mentioned method are uniform in the refractive index of the crossed parts and have less crosstalk. |
