Ultrahigh-average-power diode-pumped Nd:YAG and Yb:YAG lasers

Yttrium aluminum garnet (YAG) possesses thermal and mechanical properties that vary significantly with temperature. We show that when temperature variations are accounted for the simple scaling relationships traditionally used for high-average-power performance predictions fail. We have also found that for room temperature and below, and with uniform heat deposition in a rod, nonquadratic radial temperature profiles result and the magnitude of the thermally induced stresses are seriously underestimated. New nonlinear scaling relationships are presented that properly account for YAG materials property variations with temperature. These results are applied to diode-pumped Nd:YAG and Yb:YAG lasers operating at room temperature and 77 K; we show that significant increases in average power output are possible by operating Nd:YAG and Yb:YAG lasers at 77 K.