Formation of a non-Gaussian intensity profile in a waveguide quasi-optical resonator with an aspherical reflector

A method of phase conjugation for formation of non-Gaussian light beams with the specified transverse intensity distribution in waveguide quasi-optical resonators is described. The method is based on the correction of the phase of the fundamental resonator mode by changing the shape of one of the reflectors. The possibility of producing beams with the super-Gaussian and doughnut-like intensity profiles in a waveguide resonator with an aspherical mirror is shown theoretically. The region of geometrical parameters of the resonator is found for which the difference between the phase functions of aspherical and convex spherical resonators is small. The existence of beams with the super-Gaussian intensity profile at the output of a waveguide submillimetre (λ = 0.4326 mm) resonator with a convex spherical mirror is confirmed experimentally.