Third-order optical nonlinearity in molybdenum trioxide ($\hbox {MoO}_{{3}}$)-doped vanadium pentaoxide ($\hbox {V}_{{2}} \hbox {O}_{{5}}$) thin films

Abstract

The present work focuses on investigation of laser-induced third-order optical nonlinearity in molybdenum trioxide ($\hbox {MoO}_{\mathrm {3}}$)-doped vanadium pentaoxide ($\hbox {V}_{\mathrm {2}} \hbox {O}_{\mathrm {5}}$) thin films. $\hbox {MoO}_{\mathrm {3}}$ has been doped in $\hbox {V}_{\mathrm {2}} \hbox {O}_{\mathrm {5}}$ at different concentrations and thin films ($\hbox {MoO}_{\mathrm {3}} \!:\! \hbox {V}_{\mathrm {2}} \hbox {O}_{\mathrm {5}}$) with varying thickness have been deposited on glass substrate by standard thermal evaporation method. X-ray diffraction studies show that deposited films have orthorhombic structure and the lattice parameters change with amount of doping as well as with the thickness of the film. A Nd:YAG-pulsed laser beam having wavelength $\sim$ 532nm has been used as excitation source. Intensity-dependent absorption coefficient ($\upbeta$), nonlinear refractive index ($n_{2}$) and cubic nonlinear susceptibility ($\chi ^{3}$) have been estimated using single-beam Z-scan technique. A concentration-dependent switching of optical nonlinearity has been observed occurring due to internal self-action effects. Optical limiting behavior has also been reported with limiting threshold ($T_{L}$). Existence of strong third-order optical nonlinear susceptibility $({\upchi }^{\mathrm {3}}$) with quite low limiting threshold ($T_{L}$) for visible laser beam confirms that $\hbox {MoO}_{\mathrm {3}} : \hbox {V}_{\mathrm {2}} \hbox {O}_{\mathrm {5}}$ thin films have a great potential for the applications in photonic devices.