Abstract

I report the measured ratio of heat to stored energy for a Nd:YLF diode-pumped rod. The lasing medium is heated by nonradiative processes of the lasing ions and by direct absorption by the host. Typically, the ions are pumped to an energy level above the metastable state and, upon radiating, may terminate at a level above ground. The energy difference between the pumped energy level and the fluorescence photon energy, the quantum defect, typically contributes heat. Population quenching of the ions in the metastable state also contributes heat. The host lattice and the pump cavity walls must absorb all pump light that is not absorbed by the lasing pump light that is not absorbed by the lasing ions. This can be significant in flashlamp pumping, in diode pumping away from the absorption lines, and in lightly doped materials. The ratio of heat to stored energy was about 0.7 in a 1% atomic doped Nd:YLF rod that was diode pumped for 200 s with sigma- polarized light centered at 806 nm. This is less than the reported value of similarly pumped Nd:YAG.¹

© 1990 Optical Society of America