Reduction of thermal effects in a diode-end-pumped, composite Nd:YAG rod with a sapphire end

We present what is to our knowledge the first theoretical and experimental estimation of the thermal characteristics of a composite Nd:YAG rod with an Al2O3 (sapphire) end in diode-end-pumped geometry. The peak temperature rise in the active segment is calculated to be reduced to 66% and the focal length of the thermal lens was measured to be reduced by 20% compared with a noncomposite Nd:YAG rod. By using a composite rod we successfully demonstrated the improvement of high-power performance that is due to reduction of thermally induced birefringence, which has not been observed in a composite rod with an undoped YAG end.