Nonlinear optical characterization and optical limiting of silver nanoparticles embedded polystyrene foils

Silver (Ag) nanoparticles (< 50 nm in size) embedded polystyrene (PS) nanocomposite (PS/Ag) foils were prepared with different wt % of Ag nanoparticles into the polystyrene (PS) matrix via the solution casting method. These were studied for nonlinear optical characteristics and optical limiting behavior. The crystal structure and presence of functional groups were confirmed using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. The surface morphology, elemental composition, and spatial distribution of PS/Ag nanocomposite foils were studied by FESEM micrograph with EDX and EDS mapping that confirmed the homogeneous distribution of Ag nanoparticles throughout the PS matrix. The surface topography and roughness of the nanocomposite foils were studied with Atomic Force Microscopy (AFM). The chemical composition of the PS/Ag nanocomposite foils were studied using Raman spectroscopy which confirms the presence of D and G bands in the spectrum. The Z-scan technique was exploited to measure the optical nonlinear parameters of as-prepared PS/Ag nanocomposite foils using a continuous-wave (cw) diode laser at the wavelength of similar to 520 nm. Reverse saturation absorption (RSA) was observed in both PS and PS/Ag nanocomposite foils with different wt % of Ag which is attributed to the two-photon absorption (TPA) process. The values of nonlinear absorption coefficient (beta) and third-order nonlinear susceptibility (chi(3)) increase from 0.82 x 10(-3) to 11.7 x 10(-3) cm/W and 5.205 x 10(-7) (e.s.u) to 32.521 x 10(-5) (e.s.u) with increasing wt % of silver nanoparticles, respectively. The calculated values of nonlinear refraction (n(2)) and second-order hyperpolarizability (gamma(h)) lie in the range of - 9.16 x 10(-9) to - 3.709 x 10(-7) (cm(2)/W) and 1.525 x 10(-26)-9.530 x 10(-24) (e.s.u), respectively. The nonlinear optical (NLO) parameters of these nanocomposite foils are of great interest for photonic applications. The limiting threshold (T-L) for these nanocomposite foils was reduced to 16 mW with wt % of Ag nanoparticles that facilitated the optical limiting applications.