Fluctuation and scattering properties of RF sputtered glass thin film optical waveguides

Abstract

AbstractThe fluctuating scattering properties of a Corning 7059 glass thin‐film waveguide RF‐sputtered on pyrex glass are studied theoretically and experimentally. Light propagating in the thin film waveguide is radiated owing to imperfections of the thin film boundaries and refractive index irregularities in the film. It is thus possible to estimate the imperfection characteristics of the waveguide by comparing the measured scattering pattern with the computed data. An example of the measured results indicates that the correlation lengths of each irregularity are bx/λ ∼ 0.1 and bz/λ ∼ 1.0 and the ratio of the dispersions is G (= Vf/(Vλ)) ∼ 1.0. Here bx and bz are the correlation lengths in the film thickness direction and in the propagation direction, Vf and V are the rms values of the boundary and refractive irregularities, and λ is the wavelength. From these results it is found that both the refractive index irregularity in the thin film and the boundary irregularity contribute to the scattering loss in the glass thin‐film waveguide created by RF sputtering.