摘要:We have investigated the decay of nonequilibrium phonons in YAG:Pr3+ (1.0at.%) and LiYF 4:Pr3+ (1.0at.%) at a temperature of 9K. Nonequilibrium phonon populations at 43.0, 51.9, 66.0 and 113cm-1 are generated monochromatically with a high power pulsed far-infrared laser using defect-induced one-phonon absorption, and their temporal and spectra evolution determined using a time-resolved vibronic sideband spectrometer. We find that two decay mechanisms dominate the nonequilibrium phonon relaxation in the crystals: anharmonic decay via three-phonon-interactions and two-phonon-one-electron inelastic scattering processes. In LiYF4 system, we observe the broad band distribution that results from the anharmonic decay of the initial monochromatic phonon population. In YAG system, the latter mechanism leads to the evolution of a highly peaked phonon distribution that persists for several phonon generations.