Propagation of submillimetre laser beams in hollow waveguides

The mode and ray-optics techniques based on the representation of the input field as a spectrum of propagating modes or ray tubes are proposed for calculating the propagation of radiation in wide circular hollow waveguides excited by linearly polarised Gaussian beams. Optimal excitation conditions are determined theoretically and experimentally, and the degree of polarisation of the beams transmitted through the waveguides is evaluated.