A new longitudinal pumping scheme that uses elliptical laser beams to improve the compactness and efficiency of high-power dye lasers

Abstract

Liquid dye lasers are intrinsically suitable for high-average-power operation because their flowing laser gain media can effectively remove the heat produced by laser amplification; thus, liquid dye lasers have a significant place in various laser applications. However, to sufficiently remove the dye solution heated by the laser, a very cumbersome dye flow system is required to achieve a high flow velocity in the dye cell of a high-power dye laser, which limits its applications. In this paper, we found that the pressure and power required to drive the high-speed dye flow are both proportional to the square of the laser beam size along the direction of the flow. Based on this result, we proposed a novel longitudinal pumping scheme that uses elliptical laser beams. This new scheme can significantly reduce the size and energy consumption of dye flow loops in high-power dye lasers. We also developed a dye laser system with a main amplifier using a 1 mm × 4 mm elliptical input laser beam. The amplifier produced an average power of 135 W with a repetition rate of 10 kHz and a conversion efficiency of 39.5%. The M2 factor of the output beam was better than 1.7. The flow parameters to drive the dye flow loops were 2.1×105 Pa, and 0.43 L/s, which gave a clearing ratio of 2 for the amplifier. This new pumping scheme enables high-power dye lasers to be more compact and efficient, making them more flexible for various applications.