Abstract

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. Sato and Taira [1] recently re-measured the thermal conductivity and its temperature dependency and found that it was significantly lower than that of Nd:YVO₄. They also reported that dn/dT in the higher gain π-polarisation of Nd:YVO₄ is 7.92 at 1064 nm, compared to 10.1 for Nd:GdVO₄. One would therefore expect that Nd:YVO₄ would have weaker thermal lensing, since it is influenced by both the thermal conductivity and dn/dT. To our knowledge, a direct comparison of the thermal lens of the two materials has never been performed with equal doping concentrations and dimensions. Therefore, we aimed to compare the two materials directly under diode-end-pumping by performing thermal lens measurements during lasing with a HeNe probe beam using identical low-doped (0.15%), 4×4×18 mm³ crystals. Our setup was such that we could separately analyse the dioptric powers in the σ and π polarisations.

© 2009 IEEE