Abstract

Excited state absorption (ESA) in solid state lasers can adversely affect laser performance by decreasing the gain cross section and by introducing absorption inefficiency in the optical pump region. For the specific case of 3d³ ions, it has been shown that the ESA spectrum is highly dependent on the identity of the lowest excited state. For the ²E_g state, the ESA spectrum in the visible is a congested set of transitions to a number of higher lying doublets, whereas for the ⁴T₂ state the ESA spectrum consists of only a single ligand field transition in the visible. This is illustrated in Fig. 1 which shows a comparison of the ESA of Cr³⁺ in emerald (²E lowest excited state) and in a fluoride elpasolite (⁴T_2g lowest excited state).

© 1986 Optical Society of America