Method of forming waveguide lens having refractive index distribution.

摘要

A method of forming on a substrate (l0) a waveguide lens (l4) having a predetermined distribution of refractive index, for converging or diverging light rays which propagate through a two-dimensional waveguide (l2) formed on a surface of the substrate. The method includes a step of forming a film (l6) of a diffusion metal having a constant thickness, a step of removing local portions (l8) of said film, by using a mask so that a density of the removed local portions of the film per unit area is continuously varied, and a step of effecting thermal diffusion of the reminder of the film into the substrate. Alternatively, the method includes a step of forming a mask (24) having a multiplicity of separate openings (30) whose density per unit area is continuously varied, a step of exposing a multiplicity of separate exposed areas of the substrate aligned with the separate openings, to a material (l6) which serves to change a refractive index of the substrate, and a step of moving the material from the surface of the substrate into its interior.