Speckle correlations in the light scattered by a dielectric film with a rough surface: Guided wave effects

摘要

Diagrammatic perturbation theory is used to compute the angular intensity correlation function C(q,kq',k')=[[I(qk)-[I(qk)]][I(q'k')-[I(q'k')]] for s-polarized light scattered from a dielectric film on a perfectly conducting substrate. The scattering system supports two or more guided waves. The illuminated surface of the film is a weakly rough, one-dimensional random surface, I(qk) is the squared modulus of the scattering matrix for the system, and q,q' and k,k' are the projections on the mean scattering surface of the wave vectors of the scattered and incident light, respectively. Contributions to C include (a) short-range memory effect and time-reversed memory effect terms associated with the resonant excitation of the guided waves in the film, C-(1); (b) an additional short-range term of comparable magnitude C-(10); (c) a long-range term C-(2); (d) an infinite-range term C-(3); and (e) a term C-(1.5) that, along with C-(2), displays peaks associated with the excitation of guided waves. In contrast with the results obtained in the scattering of light from the random surface of a semi-infinite medium, interesting features arise in the speckle correlators in the present system due to the existence of the guided waves, such as various satellite peaks and a large multiplicity of resonant features. Both C-(1) and C-(2) exhibit additional peaks whose positions depend on the difference between the wave numbers of two guided waves (the most interesting case of peaks arising from guided waves), whereas C-(1.5) exhibits additional peaks whose positions depend only on the wave numbers of the guided waves taken individually. [References: 29]