Frequency degeneracy of modes in a cw solid-state laser with a planospherical resonator

An investigation was made of the influence of the resonator configuration and of distortions of a thermally induced lens in an active element on the output radiation power in the case of degeneracy of he frequencies of transverse modes of different orders. Two types of resonator were investigated in which the competition between the transverse modes, resulting in a considerable reduction in the output power, was manifested most clearly. This should make it possible to avoid such configurations in those cases when a high output multimode radiation power is required and to use these configurations when the low-order transverse modes have to be separated.