Optical Spectrum of Triply Ionized Erbium in Calcium Tungstate

摘要

The energy levels of the quadruplet I ground term of Er(3+) in single crystals of CaWO4 were established by absorption and fluorescence spectra measurements. The measurements were made using crystals at temperatures of 2, 20, and 85K. The energy level scheme allows an interpretation of the 1.612-micron four-level CaWO4:Er(3+) laser transition and shows the terminal energy level of this transition to be 318/cm above the ground state rather than 375/cm as reported by Kiss and Duncan. An effective Hamiltonian of the form suggested by Karayianis was diagonalized in a basis of Russell-Saunders wave functions to obtain the calculated energy levels and wave functions for the entire ground term of Er(3+). The calculation takes into account the complete J-mixing of the states within the ground term and is equivalent to determining the effects of the spin-orbit interaction to better than second order. (Author)