Third order nonlinearity and optical power limiting studies of PS/ZnO nanocomposite foils for photonic applications

Abstract

The present work focuses on the preparation of Polystyrene (PS) and PS/ZnO nanocomposite foils by solution casting method and study their structural and nonlinear optical (NLO) characterizations. The Zinc Oxide (ZnO) nanoparticles were synthesized by Sol-gel method. Structural analysis of the prepared nanocomposite foils was carried out by x-ray diffraction (XRD) with an estimated average crystallite size of 27.33 nm. UV–vis-NIR spectra reveal that the nanocomposite foils are transparent in the visible region. FESEM micrographs show the surface morphology of the prepared nanocomposite foils. Energy Dispersive x-ray Spectroscopy (EDX) of the prepared foils confirmed the compositional and spatial distribution of the elements. The NLO properties such as nonlinear absorption coefficient (β), nonlinear index of refraction (n2), and third-order nonlinear susceptibility were investigated by Z-scan technique at a wavelength of 532 nm and 200 mW with field intensity The values of β were found to bein the order of ∼ 10−7 cm W−1, n2 in the order of ∼10−12 cm2 W−1 and in the range 4.99 × 10−7– 38.7 × 10−7e.s.u. Further, the optical power limiting threshold was calculated to be 3.646 KW cm−2 for 8 wt % of PS/ZnO nanocomposite foil which is a better candidate to act as an optical limiter. The figure of merit has also been determined that establishes the suitability of nanocomposite foils for optical limiting and/or optical switching applications in the visible region.