Effect of laser irradiance on linear and nonlinear optoelectrical properties of PVA/copper ferrite nanocomposites

The current study investigates the impact of Q-switched Nd-YAG laser exposure on the linear and nonlinear optoelectrical properties of copper-ferrite (CuFe₂O₄) embedded polyvinyl alcohol (PVA) nanocomposites, which were fabricated using a solution casting method. The samples were irradiated using three different laser beam fluences of 19.0, 25.5, and 31.8 mJ cm^-2 at a wavelength of 355 nm for 12 minutes each. The irradiated and unirradiated nanocomposites were characterized using advanced techniques. X-ray diffraction was employed for structural analysis, Fourier transform infrared spectroscopy (FTIR) was employed to observe chemical interactions, and ultraviolet-visible spectroscopy was utilized to investigate linear and nonlinear optical properties. Exposure to laser beam yielded interesting observations: a decrease in the peak intensity of the FTIR spectra, a narrowing the direct band gap from 5.36 to 5.24 eV, an enhancement in the extinction coefficient from 2.6 × 10^-5 to 4 × 10^-5 at 400 nm, an increase in the refractive index from 1.16 to 1.2 at 300 nm, and an increase in optical conductivity from 2.7 × 10¹⁰ S cm^-1 to 4.3 × 10¹⁰ S cm^-1. Additionally, a modification in the dispersion energy from 2.39 to 3.16 eV and in the oscillator energy from 9.02 to 8.75 eV was observed. The nonlinear refractive index, the first- and third-order susceptibilities, were also enhanced. An increase in the dielectric constant was observed from 37.5 to 46.4 at 1 MHz, using a frequency response analyzer. Laser exposure enhanced the structural, optical, and dielectric properties of the nanocomposites, making it a promising material for multifunctional sensing, optoelectronics, photonics, and microelectronics.