Analysis of Nonlinear Optical Absorption Behavior by Defect States of Pure and Co-Doped V ₂O ₅ Layered 2D Nanostructures

V2O5 nanostructures doped with 1% Co synthesized by using hydrothermal method. Structural and morphological aspects, vibrational spectra and optical properties (linear and nonlinear) of pristine as well as Co-doped V2O5 (V2O5: Co) nanoparticles are investigated. X-ray diffraction patterns indicate that both V2O5 and Co doped V2O5 are stabilized in an orthorhombic structure. Energy band gaps measured using the Kubelka–Munk model give 1.94 eV for V2O5 and 1.42 eV for Co doped V2O5. When excited with 5 ns laser pulses at 532 nm in open aperture Z-scan configuration, pristine as well as Co-doped V2O5 nanoparticles are introducing an efficient nonlinear absorption behavior due to the strong reverse saturable absorption at this wavelength. Here we obtained the two-photon absorption coefficients within the range of 10−11 to 10−12 m/W, and effective three-photon absorption coefficients are in the range of 10-22 to 10-23 m3/W2. When excited at the same wavelength using a continuous wave laser beam, the effective two-photon absorption coefficient gets enhanced to 10−6m/W. These results confirm the suitability of V2O5 and Co-doped V2O5 nanoparticles as optical limiter devices in the protection of eye and sensor.