Enhanced Nonlinear Optical Limiter in the Visible Spectral Region Based on Fe- and Co-Doped NiO Nanoparticles within PVP Nanofibers

Abstract

In this study, electrospun cobalt (Co)- and iron (Fe)-doped nickel oxide (NiO) nanofilled polyvinylpyrrolidone (PVP) composite nanofibers were produced, and their linear and nonlinear optical and optical limiting properties were investigated. Three distinct average particle sizes (61, 110, and 150 nm) of Co- and Fe-doped NiO nanoparticles were produced using the coprecipitation method. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) techniques were used to analyze the morphology and structure of particles. Composite nanofibers were found to be homogeneous and continuous, with average diameters ranging from 177 to 314 nm. It was found that different particle sizes of Co- and Fe-doped NiO nanoparticles and aggregations in nanofibers did not have a significant effect on the results. The Fe-doped structure mostly contained defect states and showed the weakest fluorescence emission among the other composite nanofibers. These behaviors indicate a further charge transfer mechanism via defect states, with multiphoton absorption favoring nonlinear absorption. Open aperture Z-scan experiments were carried out at 532 nm with a 4-ns pulsed laser to observe the nonlinear optical features of nanocomposite fibers. It was observed that all of the composite nanofibers exhibited a nonlinear absorption (NA) feature, which weakened with an increase in input intensity. The Fe-doped structure, characterized by more defect states, demonstrated the strongest NA behavior. All of the composite nanofibers displayed a strong optical limiting behavior within the range of 1.35 × 10-5 and 1.92 × 10-5 J/cm2. Given the strong NA and robust optical confinement behavior of Fe-doped NiO nanoparticles, composite nanofibers have emerged as promising candidates for optoelectronic applications in the visible spectral region.