Stimulated emission investigations of effects of electron-phonon interaction in crystals activated with Nd3+ions

Stimulated emission spectroscopic methods were applied to investigate the electron-phonon interaction in Y3Al5O12and LaF3crystals activated with Nd³⁺ions. Temperature broadening and shifting of laser lines as well as the variation in the rate of nonradiative decay of the⁴ state were studied. For the Y3Al5O12-Nd³⁺crystal, the analysis of the results on temperature broadening and line shifting reveal an effective Debye temperature of ∼600 K for the spectrum of impurity-active phonons. This value of TDvery nearly corresponds to the energy of effective phonons (∼400 cm^-1) which are responsible for the nonradiative decay of the⁴ state. For LaF3-Nd³⁺the effective TDvalues obtained by two different methods are 400 and 430 K, respectively. The temperature dependence of the threshold pumping energy for both laser crystals was computed theoretically. The physical factors governing this dependence are identified.