High-Average-Power Operation of a 100-mJ-Class, Conductively Cooled, Q-switched Tm, Ho: YLF Laser

A conductively cooled Tm, Ho: YLF laser capable of producing a pulse energy higher than 100 mJ was developed. The laser crystal was cooled to -80 degrees C in order to achieve lowthreshold operation. In addition, the pumping density was optimized by using a simplified rate equation model for the Tm, Ho-codoped system so as to further reduce the laser threshold without decreasing the fractional population of the Ho upper-laser manifold in high power operations. As a result, the maximum average output power of 7.28 W was obtained at a pulse repetition frequency of 70 Hz. To the best of our knowledge, this is the highest average output power reported for a 100-mJ-class, conductively cooled, Q-switched 2 mu m laser oscillator.