Transmission and self-imaging of submillimetre laser beams in rectangular metal waveguides

The mode technique for calculating radiation propagation in rectangular metal waveguides excited by linearly polarised Gaussian beams is developed on the basis of the input field representation in the form of a spectrum of propagating modes. The conditions for optimal excitation are studied theoretically and experimentally, the degree of polarisation is calculated, and conditions for reconstruction of submillimetre beams transmitted through a waveguide are considered.