Enhanced Nonlinear Effect In Metal-dielectric-Metal Absorber Structures

With the studies on surface plasmon polaritons from noble metal growing swiftly,metamaterials with nanostructure begin to be widely applied in nonlinear optics.Metal-Dielectric-Metal(MDM)metamaterial absorbers for generating nonlinear effects are numerically investigated and fabricated.The structure has a narrow reflection dip at the resonant wavelength,which can be utilized as fundamental wavelength input for nonlinear signal measurement.The absorbers exhibit.high absorption efficiency at the dip and notably enhance the localized fundamental field,which will make a great contribution on second-and third-harmonic signal excited backwards.To Au/alumina/Au three-layer structure,the surface second harmonic generation signal from Au,which is centrosymmetric in bulk and symmetric-broken on the surface,will be enhanced by a factor over 30 in experiment,in contrast to Au/alumina surface without Au disk on the top.When the dielectric layer is replaced by an organic polymer MEH-PPV,which possesses high third order nonlinear effects,the third harmonic generation intensity from polymer will be theoretically enhanced by a factor over 10V,due to the localized fundamental field in the bulk.Both of the proposed plasmonic arrays demonstrate the potential of metamaterial absorber for further study on nonlinear photonics.