New Photonic Functions Fabricated in Oxide Glasses

Abstract

Fundamental studies of the formation of periodic structures in oxide glasses were reviewed. High spatial frequency gratings and two-dimensional sub-wavelength structures were fabricated using a combination of lithography and dry etching processes. An ultra-small demultiplexer was realized on a SiO 2 tip in which gratings, a pair of parabolic reflecting mirrors, and channel waveguides were integrated. Adopting a precisely regulated sub-wavelength structure achieved low reflectance of the SiO 2 surface. Ultraviolet laser induced structural change was useful for creating diffraction functionality. The formation of point defects with intense absorption was indispensable for inducing change of the positive refractive index of the glass. Thermally stabilized Bragg gratings and athermal waveguide filters were prepared using Ge-B-SiO 2 glass films that were irradiated with a KrF laser.