diffractive dipolar coupling in non bravais plasmonic lattices

Honeycomb plasmonic lattices are characterized by a 2-particle unit cell. The difference between the intrasublattice and intersublattice coupling is distinctive of non-Bravais lattices. Although the two particles are identical the two types of coupling may be different

Nonlinear optical properties of Au–Ag nanoplanets made by ion beam processing of bimetallic nanoclusters in silica

The nonlinear absorption of Au–Ag nanoplanets made by Ar irradiation of bimetallic nanoclusters in silica has been experimentally investigated by means of the single beam z-scan technique. The measurements have been performed in the picoseconds regime in order to isolate the fast electronic contribution to the third-order nonlinearity. The results reveal large nonlinear absorption properties of these systems, characterized by the concomitance of saturable and reverse saturable absorption. A phenomenological expression has been developed to fit the z-scan curves and to quantitatively determine the nonlinear optical parameters

VO2 Tungsten Doped Film IR Perfect Absorber

We investigated infrared reflectivity of undoped and Tungsten (W) doped Vanadium dioxide (VO2) films at varying temperatures. Undoped VO2 exhibited a clear phase transition at 100°C, achieving near 0% reflectivity, or perfect light absorption. As W doping concentration increased, the phase-transition temperature decreased, maintaining the zero-reflectivity condition. Only a 0.75% W doping enabled room temperature perfect absorption without heating the film

On the contribution of secondary fluorescence to the Fe signal in proton-induced X-ray emission channeling measurements of Fe-doped GaN

We present an experimental investigation of the contribution of secondary fluorescence to the iron signal in proton-induced X-ray emission (PIXE) channeling measurements of Fe-doped GaN layers. A method for the analysis of the PIXE angular scans has been developed, which is necessary for the correct quantification of the lattice site occupation of the Fe atoms in the GaN matrix. This approach should be taken into account any time the lattice location of small amounts of substitutional impurities has to be measured by PIXE channeling in analogous experimental conditions

Effect of geometry, anisotropy and composition on the third-order optical nonlinearities of multilayer hyperbolic metamaterials -INVITED

Quantum technologies require advanced optical metamaterials whose properties can be tailored and controlled as desired. Hyperbolic metamaterials have great potential for applications in nonlinear nanophoton-ics, such as all-optical switching, optical limiting, mode-locking and optical sensing. In this work, we show how to obtain strong third-order optical nonlinearities in hyperbolic multilayers exploiting the effect of bulk plas-mon polaritons. We demonstrate the tunability of these properties with angle and polarization, and we propose a model to predict them. We evidence the enhancement of the nonlinear response in low-loss metamaterials

Annealing behavior of high temperature implanted Fe impurities in n-InP

The lattice location of high temperature implanted Fe impurities in InP and the effect of post-implantation thermal treatments were studied by PIXE-RBS-channeling measurements. The results show that a high fraction (about 85%) of the Fe atoms is incorporated in high-symmetry sites after the high temperature implantation and most of them (more than 60%) occupy substitutional positions. Post-implantation annealing treatments induce the escape of the Fe atoms from their sites and the substitutional fraction decreases by increasing the annealing temperature. Assuming an Arrhenius behavior for this process, the activation energy for the displacement of the Fe atoms from substitutional sites is estimated to be 0.76 eV

Deep level thermal evolution in Fe implanted InP

We report on the thermal evolution of the deep levels in Fe implanted and annealed InP. The position and nature of the dominant traps have been assessed by current-voltage-temperature measurements analyzed in the framework of the space-charge-limited current model. For low temperature annealing the conduction properties of the material are controlled by a damage-related donor located at E-C-0.21 eV. A deep donor-deep acceptor electrical compensation mechanism has been assessed after high temperature annealing. The dominant traps are located at E-C-0.55 eV and E-V+0.72 eV. The latter is associated with the Fe2+/3+ center which is responsible for the semi-insulating properties

Correlation among structural, electrical, and deep-level properties of Fe centers implanted in InP

The Fe-related properties in high-temperature Fe implanted and annealed InP were studied by means of PIXE-RBS-channeling and correlated with the results of electrical (current-voltage) measurements. It is found that the point defect mobility, the concentration of substitutional Fe, and the resistivity of the implanted layer, all follow a similar temperature behavior. For annealing temperatures higher than 500degreesC semi-insulating behavior controlled by the Fe2+ deep levels is observed

Tunable Third-Order Nonlinear Optical Response in \u3f5-Near-Zero Multilayer Metamaterials

Metamaterials with properly engineered linear and nonlinear optical response are of great interest for many advanced applications in nanophotonics and quantum optics. In the present work, we perform a detailed spectral investigation of the third-order nonlinear optical properties (nonlinear refractive index and nonlinear absorption coefficient) of epsilon-near-zero Au/Al2O3 multilayer metamaterials in a broad range of the visible spectrum across their epsilon-near-zero (ENZ) wavelength, at different incidence angles with TE and TM-polarized light. Multilayers with different gold filling fractions (16 and 33%) are produced by magnetron sputtering to tune the spectral position of the -near-zero wavelength. The results demonstrate that a continuous modulation of the linear and nonlinear optical parameters of these metamaterials can be obtained as a function of the angle of incidence, with a peak of the nonlinear optical coefficients close to the ENZ wavelength. A model is proposed to describe the nonlinear optical response of the metamaterials, and an optimal agreement between experimental and simulated results is obtained in all the configurations explored. This model represents a useful tool to design multilayer metamaterials with tailored nonlinear optical properties, to be used in different experimental configurations