Thermal considerations in transverse geometries for high power copper vapour laser pumped Ti:sapphire lasers

Developed were thermal and kinetic computer models of CVL pumped Ti:sapphire slab lasers in order to assist in the design of a new Ti:sapphire slab laser. A zigzag slab resonator design such as those used in many high power solid state laser systems allows a TEM_0,0 mode to be matched to a large pumped volume. At pump powers in excess of 50 W the thermal gradients set up in the crystal create a significant astigmatic thermal lens, which can greatly complicate cavity designs incorporating the crystal. The thermal modeling has shown that the increased thermal conductivity of sapphire at cryogenic temperatures reduces the thermal relaxation time of the slab to less than the interpulse period. This yields a near flat thermal profile across the crystal at the time of lasing, with a correspondingly small thermal lens. The lens is further reduced by a six fold reduction in dn/dT from 300 K to 77 K.