Optical limiting and nonlinear optical absorption properties of C60–polystyrene star polymer films: C60 concentration dependence

Abstract

The optical limiting behavior and the nonlinear optical properties of pure C60–(polystyrenex)y (C60–(PSx)y) star polymer, and C60–(PSx)y incorporated in a polystyrene matrix, are reported. Two, four and six polystyrene arms of controllable length were grafted directly on the C60 cage, preventing aggregation of the fullerene molecule, and consequently permitting achievement of high C60 concentrations. The optical limiting behavior of these films was measured below the damage threshold, and the nonlinear absorption coefficient β was determined by the Z-scan technique, using nanosecond 532 nm and sub-picosecond 497 nm laser radiation. In some of the samples, the high concentration of C60 gives rise to intermolecular interactions, which diminish the average molecular nonlinear optical properties of the film. However, the observed dependence of the nonlinear optical properties as a function of laser pulse duration and C60 concentration may be relevant to applications of these compounds in solid state devices.