Spectroscopic analysis of Er³⁺ transitions in lithium niobate

We report on the results of a spectroscopic analysis of the transition strengths of Er-doped LiNbO3. The line strengths of several transitions from the ground state to excited state manifolds are evaluated from measured polarised absorption spectra and analysed using Judd-Ofelt theory, taking into account the crystal anisotropy. The measured and calculated oscillator strengths at 300 K compare favourably within the typical uncertainties associated with the Judd-Ofelt theory. The Judd-Ofelt parameters obtained have been used to evaluate the excited-state-absorption (ESA) transition strengths from the 4I11/2 level, which have important implications for pumping Er:LiNbO3 device