LAUSR

We report on the average power increase of a repetitively pulsed (10 Hz) nanosecond 3-µm laser due to the compensation of a strong thermal lens in the Cr:Er:YSGG laser cavity maintaining the megawatt-level peak power. Thermally-induced beam distortions are measured in a set of 3-µm erbium crystals (Er:YAG, Er:YSGG, Cr:Er:YSGG), a scheme for compensating a thermal lens in a Cr:Er:YSGG Q-switched laser with a pulse energy of 23 mJ at a repetition rate of 10 Hz in with low-order transverse mode beam is proposed and experimentally implemented. The developed approach makes it possible to control the cavity mode in high-power nanosecond 3-µm lasers with flashlamp or diode pumping, which are used for a variety of scientific and technological applications, including pumping laser crystals in the middle infrared range, as well as laser-induced microstructuring and tissue engineering.