The Dependence of Guided Optical Wave Loss in Thin-Film ZnO on Induced Surface Defect Scattering Sites

Abstract

Scattering loss in optical waveguides has primarily been investigated theoretically (1-4) and very little quantitative measurement data has been available for comparison with the theory. Where experimental comparisons have been made (3,4), the measured guided optical wave losses were higher than would be attributed to surface roughness and other volume loss mechanisms were invoked to explain the discrepancies. In the investigation described in this paper, a base propagation loss level is established in a thin-film ZnO waveguide, surface scattering sites of known density and depth are created and the corresponding increase in optical loss is measured. To the authors knowledge this is the first quantitative measurement of surface scattering losses in optical waveguides where a systematic change in the depth of the scattering sites was induced.