Thermal lens and beam properties in multiple longitudinally diode laser pumped Nd:YAG slab lasers

The focal length of the thermal lens and the beam quality factor (beam propagation factor) M/sup 2/ for a multiple longitudinally diode pumped slab laser is deduced for pump and output powers up to 16 and 4.5 W, respectively. Due to the geometry of the arrangement, a stronger thermal lens is observed in the plane with the larger pump spot radius as predicted by an analytical model for slab geometries. In addition, the second stable zone of an asymmetric resonator is found to be advantageous for improved beam properties at high output powers.