Anisotropy of nonlinear absorption in Co2+:MgAl2O4 crystal

Anisotropy of the nonlinear absorption of Co2+ ions in MgAl2O4 single crystal at the wavelengths of 1.35 and 1.54 mu m has been experimentally demonstrated. The experimental data are analyzed in the framework of a phenomenological model when the Co2+ ions are described as three sets of linear dipoles oriented along the crystallographic axes. Ground-state and excited state absorption cross-sections at 1.35 and 1.54 mu m are evaluated to be sigma(gsa) = (4.0 +/- 0.3) x 10(-19), sigma(esa) = (3.6 +/- 0.4) x 10(-20) cm(2) and sigma(gsa) = (5.1 +/- 0.3) x 10(-19), sigma(esa) = (4.6 +/- 0.4) x 10(-20) cm(2), respectively.