Formation of Laguerre-Gaussian and Non-Planar Geometric Modes in a Dye Laser Pumped through an Axicon

To form ring inversion profiles in a Rhodamine 6G dye laser (λlas ≈ 580 nm), a cuvette with an axicon was used in the 532 nm dye pumping channel. The axicon worked both in air and in the cuvette filled with liquid. By using different liquids, we can control the size of the inversion ring in the dye, exciting Laguerre-Gaussian modes (LG0l) of lower and higher orders. Non-planar geometric modes are obtained in degenerate configurations of a plano-spherical resonator. They form various discrete structures of lasing spots localized on the rings. The process of switching the lasing regime from the ring geometric mode to the LG0l mode is demonstrated when the cuvette with the axicon is filled with liquid. Experiments have shown that dye lasers are convenient objects for testing various methods of exciting structured laser beams.