Retrieval of the characteristics and determination of the parameters of statistical nanometer surface roughness using the data on scattering in a planar optical waveguide in the presence of additive noise

Abstract

Based on numerical modelling, we obtain solutions for the direct and inverse problems of waveguide light scattering by a stationary statistical nanometer-scale surface roughness in the presence of additive white noise. It is shown that the procedure developed earlier for processing far-zone scattering data (or data on the equivalent Fourier plane) yileds sufficient information on the statistical characteristics of surface roughness even for a very low level of the signal-to-noise ratio (SNR≥1). In the case of given noise with SNR≥1, the developed algorithm makes it possible to determine, within the framework of model calculations, the subwavelength correlation radii ∼ λ/20-λ/30 of the roughness with error no greater than 10-30% and the rms roughness height ∼50 A with error less than 35%.