Optical phonons effects on RE3+ lineshapes in YAG

Abstract An analysis of the optical phonons effects on the low temperature lineshapes (broadenings, asymmetries, splittings) of various absorption lines of several RE3+ ions from the beginning Pr 3+ (4 f 2 ), Nd 3+ (4 f 3 ) and end of lanthanide series Er 3+ (4 f 11 ), Tm 3+ (4 f 12 ) embedded in the same crystal, (Y3Al5O12) – YAG is presented. Most of the broadened lines are single Lorentz and asymmetric or splitted that could be described in terms of the near-resonant one-phonon emission processes involving the even components of the electron–phonon Hamiltonian and optical Raman phonons of undoped lattice. The 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+.