Short-pulsed stimulated emission in the powders of NdAl_3(BO_3)_4, NdSc_3(BO_3)_4, and Nd:Sr_5(PO_4)_3F laser crystals

Short (>300-ps) pulses of stimulated emission were found from powders of NdAl3(BO3)4, NdSc3(BO3)4, and Nd:Sr5(PO4)3F laser crystals during 532- and 805-nm excitation. Study of stimulated emission in the mixture of two powders has shown that the different components influence each other. That implies a collective behavior of emitting particles. The main features of experimentally observed stimulated emission are described with a simple model accounting for 4F3/2 excited-state concentration and emission energy density. The threshold of stimulated emission in powders is shown to be inversely proportional to the small-signal amplification along the photon path in the pumped volume.