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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 (χ⁽³⁾) were investigated by Z-scan technique at a wavelength of 532 nm and 200 mW with field intensity I_0=5.43 KW cm^(-2).The values of β were found to bein the order of ~ 10-7 cm/W, n2 in the order of ~10-12 cm2/W and χ⁽³⁾ in the range 4.99 x 10-7-38.7 x 10-7e.s.u. Further, the optical power limiting threshold was calculated to be 3.646 KW/cm2 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.

The thermal evaporation procedure was used in the current work to synthesize various compositions of neodymium-doped zinc oxide thin films with varied thicknesses on glass substrates. The Films have a hexagonal wurtzite structure, according to X-Ray Diffraction (XRD) spectroscopic research, and Nd doping cannot change this structure. Raman spectroscopy revealed peaks at 100.49, 331, 434,574, and 581 cm-1 that supported the ZnO phase, and the intensity of the peaks reduced as the quantity of dopants rose. FTIR analysis verified that Nd had completely dispersed in ZnO. Calculations of the band gap (Eg) and absorption coefficient (α) are done using absorption spectra. For all Nd doped ZnO thin films, we use the Z-Scan method to assess nonlinear optical characteristics.The samples show saturable absorption (SA) to reverse saturable absorption (RSA), the process of focusing to self-defocusing, and vice versa. The acquired value of the third-order optical non-linear susceptibility χ(3), which is the highest in comparison to earlier measurements, is of order 10-5 to 10 -6 (e.s.u.) and hence the material has potential for use in various photonic applications like optical limiter and optical switcher due to its higher values of optical non-linear parameters.

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