Experimental observation of higher order nonlinear absorption in tellurium based chalcogenide glasses

We show that highly nonlinear two-photon absorption coefficients can be obtained in infrared glasses (tellurium based chalcogenide glasses) at 1.06 mum and in the picosecond range (twice that of As2Se3). We observe an intensity-dependant two-photon absorption coefficient. This dependence is attributed to higher order effects occurring in nonlinear absorption process in our materials. The corresponding nonlinear coefficients are deduced from experimental data using a closed-form relation relating the effective two-photon absorption coefficient to the incident intensity. These coefficients become larger as the photon energy increases relative to the band gap. (C) 2003 Elsevier B.V. All rights reserved.