Comparative study of thermal lensing in low-doped Nd:YVO4 and Nd:GdVO4 of equal doping concentration

Nd:GdVO₄ is a relatively new laser material with spectral properties very similar to those of Nd:YVO₄. It was initially reported that it had almost twice the thermal conductivity of Nd:YVO₄, and therefore was said to reduce negative thermal effects. In this paper a direct comparison of the thermal lens of the two materials with equal doping concentrations and dimensions was performed. The two materials were compared directly under diode-end-pumping by performing thermal lens measurements during lasing with a HeNe probe beam using identical low-doped (0.15%), 4 times 4 times1 8 mm³ crystals. The setup was such that it be could separately analyse the dioptric powers in the sigma and pi polarisations.