Absorption and magnetic circular dichroism spectra of praseodymium doped fluorozirconate (ZBLAN) glass

Optical absorption and magnetic circular dichroism (MCD) spectra of 1% Pr3+ doped ZBLAN fluorozirconate glass have been recorded at several temperatures between 4.2 K and room-temperature. The dipole strengths of the 4f-4f transitions are parametrized in terms of three phenomenological Judd-Ofelt intensity parameters Omega(lambda) (lambda = 2, 4 and 6). The method of moments was used to extract the Faraday parameters from the MCD spectra. While the room-temperature MCD spectra are dominated by A-terms (which have the shape of the first derivative of an absorption curve), C-terms become more important at lower temperature. The temperature dependence of the P-3(0) <-- H-3(4) transition is a typical example. The temperature dependent change of the MCD spectrum can be explained by the differential thermal population of the Zeeman levels from which absorption of left and right circularly polarized light takes place.