Nonlinear photoresponse in II-VI-based nanocomposite thin films: a semiquantitative four-level model

Abstract

We have measured the one-photon, resonant nonlinear optical properties of sputter-deposited nanocomposite CdS:ZnO thin films with a characteristic grain size of about 3 nm. These films show a completely reversible photodarkening at low fluences as well as fast recovery, making them useful for optical limiting applications. The observed photoresponse can be ascribed to excited-state absorption and is in good agreement with a semi-quantitative, four-level model proposed by us. (c) 2006 Optical Society of America.