Thermal lens measurement of a LD end-pumped Nd:GdVO4 laser with stable resonator by a slit-scanning method

A simply method to measure the thermal focal length of a LD end-pumped Nd:GdVO4 solid state laser with a stable resonator is presented.By scanning a slit across the field with expression of multi-mode Gaussian distribution behind the output mirror of lasers,the radius and the M-2 factor describing the quality of beam can be measured.The waists of the multi-mode field and the TEM00 mode can be deduced according to the law of multi-mode Gassian beam propagation.Based on the ABCD matrix theory of a stable resonator,the thermal focal length of the active medium can be easily obtained.The thermal focal length of a LD end-pumped Nd:GdVO4 laser has been measured and the experimental results agree with the theoretically analyzed values.