OPTICAL ZEEMAN SPECTROSCOPY OF THE NEAR-INFRARED LASING CENTER IN CHROMIUM-FORSTERITE

Optical Zeeman spectra of the near-IR luminescent center in Cr:forster ite were obtained with an external magnetic field applied along the cr ystallographic a and c axes. The field-dependent sublevel splittings o f the triplet spin ground state were resolved through fluorescence lin e narrowing (FLN) techniques. The excellent correspondence between the observed splittings and those calculated for the tetrahedral Cr4+ cen ter, previously identified and characterized in forsterite by electron paramagnetic resonance, firmly establishes the identity of the near-I R center as tetrahedral Cr4+. A simple model for the FLN excitation-em ission cycle, including the influence of the external field on the opt ical line positions and intensities, is described.