Excited-state absorption in erbium-doped calcium lithium niobium gallium garnet

Excited-state absorption (ESA) spectra of Er3+ in the partially disordered calcium lithium niobium gallium garnet (CLNGG), recorded in the spectral range 400-900 nm, are presented and discussed. The use of a pump wavelength of 973 nm enables a complete separation of the ESA spectra from ground-state absorption (GSA) and stimulated emission. For the identification of various ESA transitions, the Er3+ energy levels above S3/24 in CLNGG are determined using GSA spectra at low temperature. Excitation spectra for the population of (S3/24,H211/22) levels by two-step sequential absorption with I13/24 as an intermediate level are generated using the recorded ESA and GSA spectra.