Reduction of scattering from a glass thin-film optical waveguide by CO2 laser annealing

Abstract

Laser annealing with a CO2 laser is utilized to improve the quality of Corning 7059 glass thin-film optical waveguides. The 1.0-μm-thick 7059 glass film is deposited by sputtering onto a thermally oxidized silicon substrate. Measurement of the absorption coefficient of 7059 glass at λ = 10.6 μm yields a value of 1.12 x 104 cm−1. Dark-field photomicrographs taken before and after laser annealing imply that both surface defects and bulk inhomogeneities are removed by laser annealing. Waveguide attenuation is measured to be 17.4 dB/cm befor laser annealing and 0.6 dB/cm afterwards.