Pump-to-mode size ratio dependence of thermal loading in diode-end-pumped solid-state lasers

The fractional thermal loading in a diode-end-pumped solid-state laser is deduced from experimental measurement of the critical pump power. The results show that fractional thermal loading critically depends on the pump-to-mode size ratio. This dependence is attributed to the effect of the pump-to-mode size ratio on the population inversion and to the effect of energy-transfer upconversion. Rigorous modeling calculations have been performed to yield a comprehensive understanding of the thermal loading in diode-end-pumped solid-state lasers.