Nonlocal and nonlinear electromagnetic effects at surfaces

Abstract

AbstractThe reflected and transmitted electric fields generated by s‐ and p‐polarized incident radiation are discussed using a microscopic approach that matches the solution of Maxwell's equation (obtained by integration over the surface region) to the incident and the reflected fields in the vacuum and to the transmitted fields in the bulk. At positions where the dielectric response is varying rapidly, the parallel components of the oscillating polarization are the sources of reflected as well as transmitted fields, and the corresponding perpendicular components (which exist only for p‐polarized incident radiation) lead to charge oscillations that are the source of both longitudinal and transverse fields. The presence of the surface makes possible the generation of transverse and longitudinal excitations with large normal components of the wave vector, whose propagation directions are given by the conservation of the parallel component of the wave vector. This formulation does not make use of additional surface boundary conditions (ABC) but requires an explicit model for the nonlocal dielectric function in the surface region. Besides discussing the fields, we discuss the choice of electromagnetic potentials. We also discuss nonlinear properties with applications to second harmonic generation.