Thermal Lensing Spectroscopy Analysis of Er:YAG Crystal Rod: Thermal Focal Length Measure

The output efficiency of Er: YAG laser is low and thermal lens effect is apparent, so it brings about great affection on quality and stability of light beam. This article has given a simple method to survey thermal lens focal length, which use CCD vidicon to extract facula data in order to fitting Gaussian beam, and then calculate equivalent thermal focal length according to changes of Gauss beam. Experiment results show that thermal lens also makes extensive effect in low-power, and if higher the pumping power, smaller the thermal focal length. The results of experiment in accordant with that of theory.