Laser performance of Ng-cut flash-lamp pumped Nd: KGW at high repetition rates

A comparative study of the flash-lamp pumped laser performance of standard b-grown Nd:KGW and Nd:KGW grown for propagation along the optical axis N-g is presented. The results show that, in comparison with b-grown crystal, the N-g-grown Nd:KGW is very promising for use at high repetition flash-lamp pumping rates. With the same laser cavity configuration, the N-g-grown Nd:KGW can operate at an average flash-lamp input power of at least 1.4 kW, while the b-cut one ceases lasing at average flash-lamp input power of similar to 0.5 kW. The reason for this is that the thermal lens induced in the N-g-oriented Nd:KGW rod under pump radiation is relatively weak, nearly spherical and positive, whereas the b-grown Nd:KGW rod acts as a quite weak positive lens for radiation with radial polarization, and as a much stronger negative lens for tangentially polarized radiation.