Analyses of 4f11 Energy Levels and Transition Intensities Between Stark Levels of Er3+ in Y3Al5O12

Abstract

ABSTRACT Absorption and fluorescence spectra obtained at temperatures as low as 4 K 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 2S+1 L J multiplet manifolds of Er3+(4f11) in D2 sites up to an energy of 44,000 cm−1. Agreement between calculated and observed Stark levels was achieved with an r.m.s. deviation of 11.2 cm−1. These transitions originate from the ground-state Stark level in the 4I15/2 manifold to J + 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 2S+1 L J multiplet manifolds between 280 and 1550 nm. For line strength measurements, the Er3+ ion is assumed to be distributed homogeneously throughout the D2 cation sites of Y3+ in the lattice. The line strengths were analyzed with a weighted (E i − C i )/E i , 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.