New channels of photon echo relaxation in Y2SiO5:Pr3+ and LaF3:Pr3+ crystals

Experimental results on the investigation of low-temperature optical absorption spectra and temperature dependence of the photon echo (PE) amplitude signal in Y2SiO5:Pr3+ and LaF3:Pr3+ crystals at the transition H-3(4)(O) - P-3(0) of the Pr3+ ion are presented. It is shown that additional relaxation channels exist for PE in addition to the known phonon mechanisms. This is associated in a LaF3:Pr3+ crystal with the temperature variation of dipole moment at the Pr3+ ion transition. In a Y2SiO5:Pr3+ crystal, this is due to the thermally activated transitions for the Pr3+ ion between nonequivalent positions in the crystal lattice. (C) 1997 American Institute of Physics.