Optical limiting of niobic tellurite glass induced by self-trapped exciton absorption of the AgCl nanocrystal dopant

Niobic tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observed at 532 nm in the UV-visible absorption spectrum. The glass structure characteristics were investigated by Raman spectroscopy, and the mechanism of self-trapped exciton was analyzed by Jahn-Teller model. Its optical limiting was measured with 532 nm picosecond laser pulses, and the corresponding nonlinear absorption coefficient was measured with open-aperture Z-scan. The experimental results showed that optical limiting at 532 nm was attributed to free carrier absorption between the self-trapped state and the continuum band. Supported by Shanghai Leading Academic Discipline Project (Grant No. B408), National Basic Research Program of China (Grant Nos. 2006CB806006, 2006CB921105), Program for Changjiang Scholars and Innovative Research Team in University, Doctoral Program of High Education (Grant No. 20050269011) and Project sponsored by Shanghai Science and Technology Committee (Grant Nos. 06DJ14008, 07dz22025, 06QH14003)