Optimal laser cavities with a hollow circular waveguide

The problem of the coupling losses experienced by the EH₁₁ fundamental waveguide mode is solved for a laser cavity formed by two mirrors and a hollow circular waveguide between them. The optimal waveguide laser cavity is defined as that with minimal internal losses in which the radiation propagates inside the waveguide in the form of the EH₁₁ mode. An analysis is made of the characteristics of the use of such cavities in lasers with a wide wavelength-tuning range.