OPTICAL LIMITING AND UP-CONVERTED LUMINESCENCE IN METALLOPORPHYRIN-DOPED SOL-GELS

In this paper, optical limiting and upconverted luminescence have been demonstrated in metalloporphyrin of ZnTPPS-doped aluminosilicate sol- gel hosts. The photo-upconverted radiative emission was observed and b elieved to result from the radiative recombination of the second excit ed singlet state. Intensity of the upconverted luminescence was found to be saturated as a function of excitation intensity. Optical limitin g associated with reverse saturable absorption was observed. These eff ects are attributed to the higher excited state absorption. A method f or determining absorption cross-section of excited states was develope d by using dynamic calculation to fit the intensity dependence of upco nverted intensity. The absorption cross sections of the excited single t and triplet state were estimated. (C) 1998 Elsevier Science Ltd. All rights reserved.