Lozano, W.de Araujo, C. B.Acioli, L. H.Messaddeq, Younes [UNESP]2014-05-202014-05-201998-08-15Journal of Applied Physics. Woodbury: Amer Inst Physics, v. 84, n. 4, p. 2263-2267, 1998.0021-8979http://hdl.handle.net/11449/37107We report the observation of negative nonlinear absorption in fluoroindate glasses doped with erbium ions. The pumping wavelength is 800 nm which is doubly resonant with Er3+ ions transitions. A large nonlinear intensity dependence of the optical transmittance and strong upconverted fluorescence are obtained. The dependence of the upconverted fluorescence intensity with the laser power is described by a system of coupled-rate equations for the energy levels' populations. (C) 1998 American Institute of Physics. [S0021-8979(98)07816-5].2263-2267engArtigo10.1063/1.368292WOS:000075257700081Acesso restritoWOS000075257700081.pdf2998503841917815