Third-order optical nonlinear properties of Co-doped V2O5 nanoparticles

Abstract

The Co-doped vanadium pentoxide nanoparticles with Co concentrations up to 20 wt. % were synthesized via a gelatin-based sol–gel route. The effect of Co substitution was investigated on the microstructural and nonlinear optical characteristics of the synthesized particles through X-ray diffraction, field effect scanning electron microscopy and Z-scan technique. The results showed that the synthesized particles consist mainly of crystalline α-V 2 O 5 phase. Co substitution results in expansion of the orthorhombic unit cell and growth of particle size from about 36–45 nm. On increasing the dopant concentration, the nonlinearity was enhanced due of the improved crystallinity, more porosity, and the increased carrier concentration. The optical nonlinearity was intensified by the power of incident laser radiation, as well. The nonlinear refractive (NLR) index, nonlinear absorption (NLA) coefficient, and nonlinear optical susceptibility are of 10 − 8 ( c m 2 / W ) , 10 − 4 ( c m / W ) , and 10 − 8 ( c m 2 / W ) order, respectively. The positive NLR index of samples originates from the self-focusing effect. Furthermore, the involved NLA coefficients are mainly related to the saturable absorption. The encouraging nonlinear optical results of V 2-x Co x O 5 suggests that this system is a promising candidate for nonlinear optical applications.