Spatial structure of light fields at Gaussian beam transmission through multilayer dielectrics under total internal reflection and waveguide excitation

An approximate analytic model is proposed to describe the field of a Gaussian beam, passing through a multilayer dielectric medium, when the process of its propagation is accompanied by the phenomena of total internal reflection (TIR) and waveguide excitation in specific media. The model assumes that the beam width is much greater than the radiation wavelength and the thickness of all bounded layers of the dielectric structure. As an example, the transmission of a Gaussian beam through a four-layer planar dielectric system is considered in order to simulate a prism scheme of waveguide mode excitation in a thin dielectric film under conditions of frustrated total internal reflection (FTIR).