Using waveguide scattering of laser radiation for determining the autocorrelation function of statistical surface roughness within a wide range of changes of the roughness correlation interval

An electrodynamic problem of laser radiation scattering in an integrated-optical waveguide containing small statistical irregularities (interface roughness and irregularities of the refractive indices of the waveguide-forming media) is considered. The possibility of using the waveguide scattering of laser radiation for extracting the information on the statistical properties of irregularities from noisy data of the scattering diagram in a far-field zone is shown. An algorithm for reconstructing the autocorrelation function of irregularities for the correlation interval changing within a wide range is described. The possibility of restoring a given Gaussian autocorrelation function that describes statistical irregularities of the waveguide substrate surface for a correlation interval changing between 10 nm and 10 μm and a high-level additive white real noise is shown by computer simulation.