Modulation of epsilon-near-zero wavelength and enhancement of third-order optical nonlinearity in ITO/Au multilayer films

We report the modulation of epsilon-near-zero (ENZ) wavelength and enhanced third-order nonlinearity in indium tin oxide (ITO)/Au multilayer films. The samples consisting five-layer 40 nm ITO films spaced by four-layer ultrathin Au different thickness, i.e., ITO(40 nm)/[Au(x)/ITO(40 nm)]4, were prepared magnetron sputtering at room temperature. ENZ is theoretically calculated experimentally confirmed. nonlinear refractive index absorption coefficient x=0, 2, 3, 4 determined using Z-scan method a 1.064 µm. large n2=1.12×10-13 m2/W β=-1.78×10-7 m/W sample x = are both four times larger than those single-layer film. optical due to enhancement carrier concentration discussed. results indicate that ITO/Au promising for advanced all-optical devices.