| 摘要 |
PURPOSE:To permit a gradual change of a refractive index on the surface of a light guide by diagonally patterning a refractive index decreasing material layer in such a manner that the area of said layer to be superposed on the light guide changes gradually. CONSTITUTION:The refractive index decreasing material layer 8 is diagonally formed on the light guide 2 formed on a substrate B. Since a diagonal line part 81 overlaps on the light guide 2, the superposition area of the refractive index decreasing material layer 8 and the light guide 2 change gradually. The refractive index decreasing material is additionally diffused in the state of diagonally patterning the refractive index decreasing material layer 8 on the light guide 2 in such a manner. The quantity of the additional diffusion is smaller in the part where the superposition area of the refractive index decreasing material layer 8 is smaller, i.e., in the part nearer the central part 23. Conversely, the quantity of the additional diffusion is larger in the part nearer an end face 21. Since the change in the quantity of the additional diffusion is gentle, the max.. value of the refractive index of light changes its position gently. The gradual change in the peak of the boundary distribution of the light in the light guide 2 is thereby permitted. |
