Measurement of στ product of solid state laser materials by an alternative method:: Application to Nd3+ doped YVO4 crystal for 4F3/2→4I11/2 transition

In this paper an alternative approach for measurement of ar product for F-4(3/2) --> I-4(11/2) transition of Nd3+ doped YVO4 crystal is reported. In this method a microchip laser is formed by keeping a small piece of the sample in plane-plane resonator and a diode laser (808 nm) is used for pumping. The pump power induced thermal lensing effect is used to make the cavity stable. The cavity mode area is estimated by measuring the thermal lens focal length at the threshold and the average pump area is measured by Gaussian fit to the intensity profiles of the pump beam. The value of sigma tau product of Nd:YVO4 crystal obtained by this method is within 10% of the reported values. The advantage of this method is that it is a simple method for direct measurement of sigma tau product of laser crystals.