Periodic sine structures on dielectric surface: numerical calculations and applications

摘要

Finite-difference time-domain technique of numerical modeling is applied to investigate scattering of plane linearly polarized monochromatic wave by sine variations of dielectric surface relief. Results of modeling include 1) space distribution of scattered light, 2) dependence of field amplification on ratio of roughness amplitude to laser wavelength, and 3) dependence of field amplification on ratio of roughness period to laser wavelength. Obtained results show that for TE polarization a) transmitted signal is more sensitive to roughness parameters than reflected one, b) there is narrow amplitude of scattered field on roughness amplitude is described by parabolic function for small values of relief amplitude. Depending on relief amplitude and period, scattering by sine roughness can result in formation of inhomogeneous space field distribution consisting of periodic field maxima inside dielectric or formation of homogeneous distribution such that both transmitted and reflected signals are close to plane wave. We consider the following applications of obtained results: 1) possibility to develop a new technique for in-situ surface roughness characterization, 2) possible mechanisms of feedbacks during laser-induced formation of surface ripples,and 3) anti-reflection effect.