Analyses of 4f Energy Levels and Transition Intensities Between Stark Levels of Er3þ in Y3Al5O12

Gary W. Burdick, John B. Gruber, Kelly L. Nash, Sreerenjini Chandra, and Dhiraj K. Sardar Department of Physics, Andrews University, Berrien Springs, MI Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, TX ABSTRACT Absorption and fluorescence spectra obtained at temperatures as low as 4K were investigated between 200 and 1550 nm on samples containing approximately 1.2 at. wt. % Er in Y3Al5O12 (YAG). Within this wavelength range 125 experimental energy (Stark) levels were analyzed, representing data that span 29 LJ multiplet manifolds of Er 3þ(4f11) in D2 sites up to an energy of 44,000 cm . Agreement between calculated and observed Stark levels was achieved with an r.m.s. deviation of 11.2 cm . These transitions originate from the ground-state Stark level in the I15=2 manifold to Jþ 1=2 Stark levels associated with each of the 28 excited-state manifolds. A total of 88 ground-state absorption transition line strengths were measured for 19 LJ multiplet manifolds between 280 and 1550 nm. For line strength measurements, the Er3þ ion is assumed to be distributed homogeneously throughout the D2 cation sites of Y 3þ in the lattice. The line strengths were analyzed with a weighted (Ei Ci)=Ei, with an r.m.s. error of 0.25. Use of a ‘‘vector crystal field’’ parametrization resolves ambiguities in the transition intensity parameters and allows for the definition of polarization-resolved Judd-Ofelt parameters, which may have wide-ranging applicability for future Judd-Ofelt-type intensity calculations.