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A study of the solvent temperature effects in a single longitudinal mode pulsed dye laser

The effect of the dye solution temperature in a single longitudinal mode pulsed dye laser pumped by a copper vapor laser was studied in detail. The study was carried out using a laser wavelength meter. It was experimentally observed that the wavelength tuning of the single mode dye laser with respect to the optical path length was limited to a grating pass band of 2.5 GHz beyond which a second mode appeared, a mode hop occurred and the laser wavelength settled at a new value. We observed cyclic behavior of single to two mode oscillation when the cavity length was changed continuously in one direction. The wavelength jitter band was observed to be ∼2.5 pm for two mode oscillation while it was ∼0.5 pm for single mode oscillation. By stabilizing the dye solution temperature to a set value of 20 ± 0.15 °C the cyclic behavior was eliminated and only a small drift of 1.4 pm was obtained over more than 30 min of operation. The wavelength change was attributed to variation of the optical path length due to variation of the refractive index with temperature. The cyclic behavior of single mode to two modes was established by applying voltage to the end mirror PZT, which changed the cavity length with a resolution of 8.5 MHz nm−1.