Enhanced 2PA nonlinear absorption and optical limiting behavior of pure, unitary and binary doped CuO nanoparticles underneath laser excitation

Pure, unitary (Zn & Bi), and binary-doped (Zn/Bi) CuO nanoparticles were synthesized using Moringa oleifera leaf extract. XRD analysis confirmed the monoclinic phase, and the incorporation of Zn 2+ . and Bi 3+ . into Cu 2+ . ions was observed. FT-IR spectra provided molecular vibration data, while FE-SEM revealed various nanostructures (spherical, nanorods, riceshaped, and nanoplates). EDAX analysis showed the elemental compositions of Cu, O, Zn, and Bi. Zeta potential measurements indicated negative charges of -34.23 mV, -33.86 mV, -32.6 mV, and -32.0 mV for pure, Zn-doped, Bi-doped, and Zn/Bi-doped CuO nanoparticles. UV-Vis spectra revealed a robust absorption peak in the 256-276 nm range, and the optical bandgap was determined. PL spectra indicated peak intensity growth due to oxygen defects. Nonlinear optical properties were studied using the Z-scan technique, and Bi-doped CuO exhibited superior nonlinear absorption and optical limiting behavior, making it a promising candidate for laser damage protection.