Optical detection of near infrared femtosecond laser-heating of Er3+-doped ZnO-Nb2O5-TeO2 glass by green up-conversion fluorescence of Er3+ ions

The green up-conversion fluorescence of Er3+ ions doped in an nonlinear optical ZnO-Nb2O5-TeO2 glass was observed by using 800 nm excitation from a regenerative femtosecond (fs) Ti:Sapphire laser. The detailed analysis on two fluorescence lines at 526 nm (H-2(11/2)-I-4(15/2)) and 548 nm (S-4(3/2)-I-4(15/2)) revealed the fs laser heating of the multi-component TeO2-based glass, which was possibly due to its nonlinear absorption of the host glass via the imaginary part of the third-order optical susceptibility (chi((3))). The result was compared with that of a Er3+-doped aluminosilicate glass under the same irradiation condition. When the fs laser was irradiated to the multicomponent TeO2-based glass in the power density of 150 TW/cm(2), the laser spot was heated up to similar to 520 K, which however was still less than the glass transition temperature (T-g=688 K). This technique provides a useful sensing method of laser spot temperature even inside transparent materials. (C) 2010 Elsevier B.V. All rights reserved.