Effect of thermal lens on beam quality and mode matching in LD pumped Er–Yb-codoped phosphate glass microchip laser

The theoretical values of the thermal focal length and laser beam waist are derived from the theoretical model and transformation theory, respectively. The values of thermal focal length, laser beam waist and the far field divergence angle were experimentally measured in a laser diode (LD) pumped erbium?ytterbium(Er?Yb)-codoped phosphate microchip glass laser. As an extension of thermal effect studies, we investigate the role of thermal lens on beam quality and the mode matching between the pump and the laser, which affects laser efficiency in TEM00 operation. The study shows that the experimental data are in good agreement with the theoretical predictions.