Nonlinear Optical Studies of [Pt₁₇(CO)₁₂(PPh₃)₈]^<i>n</i>+ Metal Nanoclusters and Their Enhancement via All-Plastic Photonic Crystal Cavity

Abstract

Metal nanoclusters of atomic precision have recently emerged as potential candidates for nonlinear optical applications owing to their strong quantum confinement effects. Herein, we report the nonlinear absorptive and refractive properties of platinum-17 (Pt17) metal nanoclusters stabilized by carbon monoxide and triphenyl phosphine ligands. The open aperture z-scan studies in the nanosecond regime reveal a transmittance dip at the focus characteristic of molecule-like behavior and discrete energy levels. The clusters also exhibited a significantly lower optical limiting threshold value and self-defocusing behavior which can be deployed to resist intense optical radiation. We also demonstrate a photonic crystal cavity-assisted enhancement in the absorptive nonlinearity of the synthesized clusters as a result of intense field localization in the defect layer. Our study throws light on the application of these ultrasmall structures in nanophotonic devices.