Waveguide resonator with wavefront-reversing mirrors

A study is made of the properties of waveguide resonators with wavefront-reversing mirrors, of the spatial structure of radiation in such resonators, and of resonator mode losses. It is shown that wavefront reversal can ensure that the resonator modes are identical with the waveguide modes and that their losses and selectivity are due to the losses in the waveguide and are independent of the dispersion of the phases of the waveguide modes.