Optical-absorption intensities and intermanifold emission cross sections of trivalent erbium ions in calcium fluorophosphate

Abstract

A spectroscopic analysis is performed on trivalent erbium ions, Er3+, doped into calcium fluorophosphate (FAP) to assess this material for its potential as a near-infrared laser host. The Judd-Ofelt model is applied to the orientation-averaged, room-temperature absorption intensities of Er3+ in FAP to obtain the phenomenological intensity parameters: Ω2=5.86×10−20cm2, Ω4=0.38×10−20cm2, and Ω6=0.88×10−20cm2. The intensity parameters are used to determine the radiative decay rates (emission probabilities), radiative lifetimes, and branching ratios of the Er3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds LJ2S+1 of Er3+ in FAP. Using the radiative decay rates for Er3+ transitions between the corresponding excited states and the lower-lying states, the radiative lifetimes of eight excited states are determined in this host. The room temperature fluorescence lifetime and the radiative lifetime of the Er3+I13∕24→I15∕24(1.53μm) transition are reported and the quantum efficiency is determined to be 69% for 1.0wt%Er3+:FAP. In addition, the orientationally resolved emission cross sections for the S3∕24→I15∕24 and I13∕24→I15∕24 transitions are presented.