Zinc Phthalocyanine-Poly (Vinyl Alcohol) nanocomposite films: Low threshold optical limiting properties based on third-order nonlinear absorption response

Abstract

In this article, we discuss on an in-depth study of the structure and morphology as well as optical (linear/nonlinear) properties of Zinc Phthalocyanine (ZnPc) - Poly (Vinyl Alcohol) (PVA) nanocomposite films. An investigation into the third-order nonlinear absorption properties of the nanocomposite films of ZnPc-PVA system, on excitation with low power continuous wave (CW) laser light at 632.8 nm, for different concentrations of the ZnPc content and at different input intensities, is presented. In these nanocomposites, a transition from Saturable Absorption (SA) to Reverse Saturable Absorption (RSA) was observed, on either increasing fluence or ZnPc content. The estimated values of the effective coefficients of nonlinear absorption (β) and imaginary third-order nonlinear susceptibility (Imχ(3)) are better than those reported ones. Furthermore, the optical limiting action of these samples is demonstrated. The results suggest that the nanoclustered organic chromophores are dispersed uniformly in the voids/free volumes available between the PVA chains. Standing on these points, it may be noted that the newly fabricated ZnPc-PVA nanocomposite films, which possess excellent surface homogeneity, high laser damage threshold, improved thermal and photostability, and prolonged lifespan (five years or more!), represent an efficient low threshold NLO material with significant potential applications in optoelectronic and photonic devices.