Temperature Effects in Rhodamine B Dyes and Improvement in CW Dye Laser Performance

The effect of cooling the laser medium on the lasing characteristics of an organic cw dye laser, Rhodamine B in ethylene glycol, pumped by an Argon laser was examined. Significant improvements in the performance of this dye laser were achieved as the solvent temperature was reduced below room temperature, namely: a significant reduction in the threshold power requirements and a considerable increase in the attainable output power. The results obtained may be understood in terms of increased quantum yield of the RhB dye as the temperature is reduced. This effect overrides possible negative effects that are normally expected due to intermolecular relaxation processes and which are normally observed for other dye lasers which already have high quantum yields at room temperature.