Reduction of thermally induced lenses in Nd:YAG with low temperatures

At high pump powers, Nd:YAG lasers suffer from thermally induced optical effects such as graded-index lenses, birefringence, and bi-focusing. Due to more favorable material properties at low temperatures, the thermal lenses are significantly reduced by cryogenic cooling. In the present study, we measured the thermal lens in a Nd:YAG rod to be reduced by more than an order of magnitude when cooled with liquid nitrogen.