Third-order nonlinear optical properties of NiFe2O4 nanoparticles by Z-scan technique

In this research, NiFe2O4 nanoparticles was prepared using different sintering temperature. In addition to characterization of nanoparticles via X-ray diffraction (XRD), scanning electron microscopy (SEM), and FTIR spectra, the nonlinear optical (NLO) properties of nanoparticles was estimated by the Z-scan method with continuous wave (CW) He:Ne laser at 632.8 nm. According to XRD results of 750° and 850° of NiFe2O4 spectra by increasing the temperature, the intensity, and broadening of peaks are decreased that it is clearly referred to more crystallization and raising the size of particles. The histogram of the NiFe2O4 nanoparticles size distribution is 42, 96, and 315 nm at 750 °C, 850 °C, and 950 °C, respectively. Furthermore, the more than 93% of the NiFe2O4 nanoparticles are in the size range from 25 to 50 nm, 50 to 110 nm, and 150 to 400 nm at 750 °C, 850 °C, and 950 °C sintering temperatures, respectively. The nonlinear refractive (NLR) indices and nonlinear absorption (NLA) coefficients of the synthesized samples are obtained in the order of 10−7 cm2/W with a negative sign and 10−3 cm/W, respectively. The origin of optical nonlinearity may be attributed due to the presence of two-photon absorption (TPA) effect.