Continuous-wave garnet ring laser emitting single-mode linearly polarized radiation and intracavity second harmonic generation in LilO3

An investigation was made of a method of selecting the TEM₀₀ mode in a laser by using birefringence induced in an active element during pumping. The reasons for astigmatism of the thermal lens in an active element with Brewster-cut faces were determined and an investigation was made of the structure of the radiation field of a laser using such an element. It is found that the optimal conditions for efficient emission of linearly polarized radiation in the dominant transverse mode in a laser with a Brewster active element are achieved by using an active element of rectangular cross section with a specific ratio of the sides. A prototype YAG ring laser emitting linearly polarized radiation with a power of 15 W in the TEM₀₀, mode is described. By using an LilO₃ nonlinear element, 0.43 W of cw radiation at the 0.53 μ wavelength is obtained.