Optical and sign-flipping nonlinear optical properties of NiO/PMMA/PANI nanocomposite films

In this study, we introduce an efficient nanocomposite system to enhance optical properties of Nickel oxide (NiO) integrated with two polymers matrix. NiO nanoparticles is prepared using chemical co-precipitation method and its nanocomposite films (NCFs) were prepared with poly methyl methacrylate (PMMA) and polyaniline (PANI) using drop-casting method on glass substrate and was optimized by changing the concentration of NiO. The prepared NCFs were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), ultraviolet (UV)-visible absorption spectroscopy, photoluminescence (PL) spectroscopy and X-ray photoelectron (XPS) spectroscopy. The open-aperture z-scan method is employed for nonlinear optical investigations, utilizing a nanosecond pulsed laser with a wavelength of 532 nm for excitation. The findings indicate that the NCFs exhibit sign-flipping nonlinear behavior, indicating a transition from saturable absorption to reverse saturable absorption. This suggests that our NCFs exhibit optical limiting properties and potential for applications in photonic devices, such as optical switches and laser protection systems.