Strip-loaded waveguide formed in a graded-index LiNbO(3) planar waveguide.

An As(40)Se(50-x)S(x)Ge(10) film strip loaded waveguide, formed in the graded-index LiNbO(3) planar waveguide, has been demonstrated. Analytical results show that the optical field confinement in the waveguide loaded by the high refractive index film becomes large near the film cutoff thickness for the fundamental mode. Photostructural effect of the chalcogenide glass overcomes difficulty in precisely controlling film thickness. A 3-D waveguide has been achieved by loading As(40) Se(10)S(40)Ge(10) film 10 microm wide on a Ti diffused LiNbO(3) planar waveguide. Optical confinement in the waveguide has been improved intensively with the aid of the photostructural effect of the film.