Photoinduced changes in a Sudan I doped PMMA thin film

Department of physics, Shanghai Jiao Tong University, Shanghai 200240, P.R. China

Corresponding author: cswang@sjtu.edu.cn

Received: 5 May 2008
Revised: 24 July 2008
Accepted: 16 September 2008
Published online: 6 December 2008

Abstract

Photoinduced changes in a Sudan I doped PMMA thin film were investigated. The dependence of photoinduced birefringence of the thin film on light intensity was studied, with a continuous wave (CW) 532 nm laser as pump light and a CW 650 nm laser as probe light. For all the light intensities (100–1000 mW/cm²), the thin film possessed large photoinduced birefringence (Δn ~ 10⁻⁴). With a CW 532 nm laser at relatively low light intensity, a reversible polarization hologram has been recorded in the thin film. Moreover, Z-scan measurements showed that the thin film possessed large nonlinear refractive index (−7.93 × 10⁻⁵  cm ²/W) and nonlinear absorption coefficient (−5.50 W/cm) under a CW 532 nm excitation.