Optical theory of Gaussian beam transmission through a hollow circular dielectric waveguide

Abstract

An optical theory is developed to calculate the power transmission of a Gaussian beam through a hollow circular dielectric waveguide. This theory uses Fresnel formulas of wave reflection on a dielectric wall and approximate formulas of Gaussian beam diffraction through a circular aperture. The calculation is valid for low-loss waveguides and for beams weakly diffracted by the guide aperture. These conditions are fulfilled in most of the usual cases. The results agree well with theoretical relations derived from propagation constants of modes. An application is made to the waveguides used in the infrared interferometer for the JET tokamak.