Influence of optical inhomogeneity in the gain medium on the bandwidth of a high-repetition-rate dye laser pumped by copper vapor laser

Fluctuations in output of a pulsed dye laser are inevitable and seriously affect the realization of their full potential as a narrow-bandwidth tunable source. High-repetition-rate dye lasers require the flow of the dye solution to be at sufficiently high speed across the pump region so as to replace the heated medium and move it away from the dye laser axis. This introduces instabilities and fluctuations in the lasing medium, thereby affecting the bandwidth and wavelength of the dye laser. We report the effect of optical inhomogeneity in the gain medium on the bandwidth of a rhodamine 6G dye laser transversely pumped by a copper vapor laser. It is observed that the bandwidth of the dye laser decreases with increasing Reynolds number within the laminar region of flow.