Temperature Effects in Rhodamine B Dyes and Improvement in CW DyeLaser Performance

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