Mode discrimination and coupling losses in rectangular-waveguide resonators with conventional and phase-conjugate mirrors

Coupling efficiencies and mode discrimination in coaxial waveguide laser resonators

“…Since the first demonstration of the operation of a waveguide gas laser by Smith [1], considerable interest in waveguide lasers has been developed [2][3][4][5][6][7] because of their impressive potential in applications. When governed by the requirements of compactness and high beam quality, the design of waveguide resonators demands a delicate balance between its loss-tolerance level and its ability to discriminate among various transverse modes.…”

“…The coupling losses determine the extent to which a waveguide mode is coupled back onto itself after being reflected from the resonator mirrors, and play a crucial role in determining the properties of waveguide resonators [3]. Abrams [2], Degnan and Hall [3], Avrillier and Verdonck [5] and Boulnois [6] have studied the single mode losses of resonators in the hollow circular waveguide and rectangular waveguide (including square waveguide), respectively, and report that there exist three special geometries to provide the lowest coupling losses, corresponding to plane-parallel, half-concentric and semiconfocal configurations. In recent years coaxial waveguides have been increasingly used for gas lasers operating with RF transverse excitation and diffusion cooling [7,8].…”