Ti:sapphire has emerged as a significant new solid-state laser material over the past few years. Its robust nature and broad tuning range make this material appropriate for many high-power applications. Scaling Ti:sapphire to high powers can be achieved by taking advantage of the thermal properties of the material at low temperatures.1,2 By cooling sapphire to liquid-nitrogen temperatures from room temperature, the thermal conductivity increases by a factor of 30, and the change in index of refraction with respect to temperature (dN/dT) decreases by a factor of 7. These effects greatly reduce the thermally induced optical distortions in Ti:sapphire laser rods under high pump powers. Recent work by Schultz and Henion3 suggests that 1-kW Ti:sapphire lasers are possible in a rod geometry by cooling with liquid nitrogen. Schultz and Henion3 have demonstrated 350 W of quasi-cw output power under thermal steady-state conditions.
© 1991 Optical Society of AmericaPDF Article