Refractive index gradients and dye solution flow characteristics in pulsed copper vapor laser pumped dye laser cells

A study of dye solution flow characteristics in a planar dye laser cell, and their influence on the thermal properties affecting the optical quality of the lasing medium, particularly thermal lensing, is presented. Steady temperature gradients generated in the dye laser cell (∼10^{- 3} M rhodamine-6G in methanol) by a high-frequency repetitive copper vapor laser, extended from 1 to 2 mm upstream relative to the pump laser impact position to the entire cell length downstream. The steady nature of the gradients is related to vorticity of the dye solution flow, resulting in a 3-4 orders of magnitude apparent enhancement of the thermal diffusivity.