Optical resonators with periodic boundaries

A theoretical and experimental study of Fabry-Perot resonators with periodic boundaries is described. The solution of the parabolic equation of a boundary-value problem of electrodynamics is used as a basis to determine the natural modes of such resonators, and to calculate the near- and far-field spatial distributions. The existence of periodic natural modes is demonstrated. Experimental data obtained with a neodymium glass-laser resonator with modulated reflecting power are analyzed. Resonators of the type discussed are shown to be capable of generating extremely narrow laser radiation patterns.