Plasmon resonances in coupled Babinet complementary arrays in the mid-infrared range

A plasmonic structure with transmission highly tunable in the mid-infrared spectral range is developed. This structure consists of a hexagonal array of metallic discs located on top of silicon pillars protruding through holes in a metallic Babinet complementary film. We reveal with FDTD simulations that changing the hole diameter tunes the main plasmonic resonance frequency of this structure throughout the infrared range. Due to the underlying Babinet physics of these coupled arrays, the spectral width of these plasmonic resonances is strongly reduced, and the higher harmonics are suppressed. Furthermore, we demonstrate that this structure can be easily produced by a combination of the nanosphere lithography and the metal-assisted chemical etching technique

Evidence for critical scaling of plasmonic modes at the percolation threshold in metallic nanostructures

In this work we provide the experimental demonstration of critical scaling of plasmonic resonances in a percolation series of periodic structures which evolve from arrays of holes to arrays of quasi-triangles. Our observations are in agreement with the general percolation theory and could lead to sensor and detector applications

Transparent metal electrodes from ordered nanosphere arrays

We show that perforated metal electrode arrays, fabricated using nanosphere lithography, provide a viable alternative to conductive metal oxides as transparent electrode materials. The inter-aperture spacing is tuned by varying etching times in an oxygen plasma, and the effect of inter-aperture “wire” thickness on the optical and electronic properties of perforated silver films is shown. Optical transmission is limited by reflection and surface plasmons, and for these results do not exceed 73%. Electrical sheet resistance is shown to be as low as 3 Ω ◻−1 for thermally evaporated silver films. The performance of organic photovoltaic devices comprised of a P3HT:PCBM bulk heterojunction deposited onto perforated metal arrays is shown to be limited by optical transmission, and a simple model is presented to overcome these limitations

Role of interactions in the magneto-plasmonic response at the geometrical threshold of surface continuity

The optical and magneto-optical behavior in periodically nanostructured surfaces at the threshold of surface continuity is revealed. We address Co films that evolve from an island-like array to a connecting network of islands that form a membrane pattern. The analysis of magneto-optical spectra as well as numerical simulations show significant differences between continuous and broken membranes that depend dramatically on the energy of the incoming radiation. Light localization increases the magneto-optical signal in the membranes. However, the generation of hot spots is not accompanied with magneto-optic enhancement. The electromagnetic field profile within the membrane system can explain the differences in the transmission and in the magneto-optic Kerr signal

Enhanced broad-band extraordinary optical transmission through subwavelength perforated metallic films on strongly polarizable substrates

We demonstrate through simulations and experiments that a perforated metallic film, with subwavelength perforation dimensions and spacing, deposited on a substrate with a sufficiently large dielectric constant, can develop a broad- band frequency window where the transmittance of light into the substrate becomes essentially equal to that in the film absence. We show that the location of this broad-band extraordinary optical transmission window can be engineered in a wide frequency range (from IR to UV), by varying the geometry and the material of the perforated film as well as the dielectric constant of the substrate. This effect could be useful in the development of transparent conducting electrodes for various photonic and photovoltaic devices

A broadband solar absorber with 12 nm thick ultrathin a-Si layer by using random metallic nanomeshes

We show in theory, simulations, and experiments that, by applying random metallic nanomeshes, a broad-band multilayered structure with a 12 nm thick a-Si film as the active layer can absorb 89% of the total solar energy in the visible range from 400 nm to 700 nm. Such broadness and high absorption can be attributed to the random scattering introduced by the aperiodic metallic nanomeshes and the plasmonic-metamaterial design. The broadband and smooth electromagnetic response, combined with a very high absorption, is desired for solar energy harvesting devices, making this structure a good candidate for high efficiency photovoltaics with ultra-thin active layers

Symptomatic Giant Cavernous Haemangioma of the Liver: Is Enucleation a Safe Method?

Twenty-three patients with symptomatic giant hemangioma of the liver were treated by surgery between 1979 and 1996 at the department of General Surgery, Faculty of Medicine, University of Çukurova. Twenty-three enucleations were performed in 21 patients, left lateral segmentectomy in one patient and enucleation plus left lobectomy in one patient. The tumors were enucleated along the interface between the hemangioma and normal liver tissue. The diameters of the tumors ranged from 5×5 to 25×15 cm. The mean blood loss for enucleations was 525 ml (range 500–1000 ml). There was no mortality and no postoperative bleeding. Three patients had postoperative complications. Enucleation is the best surgical technique for symptomatic giant hemangioma of the liver. It may be performed with no mortality, low morbidity and the preservation of all normal liver parenchyma

Observation of a hole-size-dependent energy shift of the surface-plasmon resonance in Ni antidot thin films

A combined experimental and theoretical study of the magneto-optic properties of a series of nickel antidot thin films is presented. The hole diameter varies from 869 down to 636 nm, while the lattice periodicity is fixed at 920 nm. This results in an overall increase of the polar Kerr rotation with decreasing hole diameter due to the increasing surface coverage with nickel. In addition, at photon energies of 2.7 and 3.3 eV, where surface-plasmon excitations are expected, we observe distinct features in the polar Kerr rotation not present in continuous nickel films. The spectral position of the peaks exhibits a red shift with decreasing hole size. This is explained within the context of an effective medium theory by a change in the effective dielectric function of the Ni thin filmsH.F. gratefully acknowledges China Scholarship Council (CSC) for financial support and André Schirmeisen for the data of Ni film. A.G.-M. and B.C. acknowledge funding from Spanish Ministry of Economy and Competitiveness through grants “FUNCOAT” CONSOLIDER CSD2008-00023 and “MAPS” MAT2011-29194-C02-01. J.C.C. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (Contract No. FIS2011-28851-C02-01) and from the Comunidad de Madrid (Contract No. S2013/MIT- 2740). E.M.A. and M.G. acknowledge financial support by the European Union under the project CosmoPHOS with the number “310337

Observation of a hole-size-dependent energy shift of the surface-plasmon resonance in Ni antidot thin films

© 2015 AIP Publishing LLC. A combined experimental and theoretical study of the magneto-optic properties of a series of nickel antidot thin films is presented. The hole diameter varies from 869 down to 636 nm, while the lattice periodicity is fixed at 920 nm. This results in an overall increase of the polar Kerr rotation with decreasing hole diameter due to the increasing surface coverage with nickel. In addition, at photon energies of 2.7 and 3.3 eV, where surface-plasmon excitations are expected, we observe distinct features in the polar Kerr rotation not present in continuous nickel films. The spectral position of the peaks exhibits a red shift with decreasing hole size. This is explained within the context of an effective medium theory by a change in the effective dielectric function of the Ni thin films.H.F. gratefully acknowledges China Scholarship Council (CSC) for financial support and André Schirmeisen for the data of Ni film. A.G.-M. and B.C. acknowledge funding from Spanish Ministry of Economy and Competitiveness through grants “FUNCOAT” CONSOLIDER CSD2008-00023 and “MAPS” MAT2011-29194-C02-01. J.C.C. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (Contract No. FIS2011-28851-C02-01) and from the Comunidad de Madrid (Contract No. S2013/MIT-2740). E.M.A. and M.G. acknowledge financial support by the European Union under the project CosmoPHOS with the number “3100337”.Peer Reviewe