Optical phonons effects on RE3+ lineshapes in YAG

An analysis of the optical phonons effects on the low temperature lineshape s (broadenings, asymmetries, splittings) of various absorption lines of sev eral RE3+ ions from the beginning Pr3+ (4f(2)), Nd3+(4f(3)) and end of lant hanide series Er3+ (4f(11)), Tm3+ (4f(12)) embedded in the same crystal, (Y 3Al5O12) - YAG is presented. Most of the broadened lines are single Lorentz and asymmetric or splitted that could be described in terms of the near-re sonant one-phonon emission processes involving the even components of the e lectron-phonon Hamiltonian and optical Raman phonons of undoped lattice. Th e shape of other lines observed especially in Nd3+ and Pr3+ spectra is also analyzed. The spread of widths of Lorentz lines suggests a decreasing from Pr3+ to Nd3+ and an increasing from Er3+ to Tm3+. (C) 2001 Elsevier Scienc e B.V. All rights reserved.