arXiv subjects

Miriam Deutsch

Publications and source records attributed to Miriam Deutsch.

11 recordsLinked to original sources

arXiv2015

Tunable Geometric Fano Resonances in a Metal/Insulator Stack

We present a theoretical analysis of surface-plasmon-mediated mode-coupling in a planar thin film metal/insulator stack. Solving for the modes of this structure, we obtain an avoided crossing in the angular domain that is tunable using the system's materials and geometrical parameters. The computed reflectance of the metal/insulator stack exhibits a lineshape that is modeled as a geometric Fano resonance, accompanied by a response function characteristic of an induced coherence, albeit in the angular domain. We also observe a reversal of the Fano lineshape asymmetry as the system's parameters are varied. We attribute this \emph{q}-reversal to an interloping background radiation field comprising the surface plasmon polariton mode.

physics.optics↗

arXiv2013

Coupled-Plasmon-Controlled Transmission in Distributed Bragg Structures

Using the finite element method we investigate plasmon-mediated transmission in a periodically modulated metal-insulator-metal (MIM) grating. We compute the eigenmodes of a silver-silica-silver conformal coating atop an array of close-packed silica rods, and correlate them with extinction and transmission characteristics of the structure. We observe efficient coupling of impinging plane-waves to gap plasmon modes, allowing control of both bandwidth and intensity of the transmitted radiation.

physics.optics↗

arXiv2011

Asymmetric Reflectance and Cluster Size Effects in Silver Percolation Films

We develop a quantitative description of giant asymmetry in reflectance, recently observed in semicontinuous metal films. The developed scaling-theory based technique reproduces the spectral properties of semicontinuous composites, as well as provides insight into the origin of experimentally observed loss, reflectance, and transmittance anomalies in the vicinity of the percolation threshold.

physics.optics↗

arXiv2011

Tunable asymmetric reflectance in silver films near the percolation threshold

We report on the optical characterization of semicontinuous nanostructured silver films exhibiting tunable optical reflectance asymmetries. The films are obtained using a multi-step process, where a nanocrystalline silver film is first chemically deposited on a glass substrate and then subsequently coated with additional silver via thermal vacuum-deposition. The resulting films exhibit reflectance asymmetries whose dispersions may be tuned both in sign and in magnitude, as well as a universal, tunable spectral crossover point. We obtain a correlation between the optical response and charge transport in these films, with the spectral crossover point indicating the onset of charge percolation. Such broadband, dispersion-tunable asymmetric reflectors may find uses in future light-harvesting systems.

physics.optics↗

arXiv2010

Surface plasmon based thermo-optic and temperature sensor for microfluidic thermometry

We report on a non-interacting technique for thermal characterization of fluids based on surface plasmon resonance interrogation. Using liquid volumes less than 20 micro liters we have determined the materials' thermo-optic coefficients with an accuracy of better than 10^{-5} 1/°C and demonstrated temperature sensing with an accuracy of 0.03 °C. The apparatus employs a low-power probe laser, requiring only a single wavelength, polarization and interrogation angle for accurate characterization. The device is particularly suited for precise diagnostics of liquids and gases within microfluidic systems, and may also be readily integrated into a variety of lab-on-chip platforms, providing rapid and accurate temperature diagnostics.

physics.optics↗

arXiv2007

Curvature-induced radiation of surface plasmon polaritons propagating around bends

We present a theoretical study of the curvature-induced radiation of surface plasmon polaritons (SPPs) propagating around bends at metal-dielectric interfaces. We explain qualitatively how the curvature leads to distortion of the phase front, causing the fields to radiate energy away from the metal-dielectric interface. We then quantify, both analytically and numerically, radiation losses and energy transmission efficiencies of SPPs propagating around bends with varying radii- as well as sign-of-curvature.

physics.optics↗

arXiv2007

Metamaterial Coatings for Broadband Asymmetric Mirrors

We report on design and fabrication of nano-composite metal-dielectric thin film coatings with high reflectance asymmetries. Applying basic dispersion engineering principles to model a broadband and large reflectance asymmetry, we obtain a model dielectric function for the metamaterial film, closely resembling the effective permittivity of disordered metal-dielectric nano-composites. Coatings realized using disordered nanocrystalline silver films deposited on glass substrates confirm the theoretical predictions, exhibiting symmetric transmittance, large reflectance asymmetries and a unique flat reflectance asymmetry.

physics.optics↗

arXiv2006

Plasmon Assisted Transparency in Metal--Dielectric Microspheres

We present a theoretical analysis of light scattering from a layered metal-dielectric microsphere. The system consists of two spherical resonators, coupled through concentric embedding. Solving for the modes of this system we find that near an avoided crossing the scattering cross section is dramatically suppressed, exhibiting a tunable optical transparency. Similar to electromagnetically induced transparency, this phenomenon is associated with a large group delay, which in our system is manifest as flat azimuthal dispersion.

physics.optics↗

arXiv2006

Enhanced surface plasmon resonance absorption in metal-dielectric-metal layered microspheres

We present a theoretical study of the dispersion relation of surface plasmon resonances of mesoscopic metal-dielectric-metal microspheres. By analyzing the solutions to Maxwell's equations, we obtain a simple geometric condition for which the system exhibits a band of surface plasmon modes whose resonant frequencies are weakly dependent on the multipole number. Using a modified Mie calculation, we find that a large number of modes belonging to this flat-dispersion band can be excited simultaneously by a plane wave, thus enhancing the absorption cross-section. We demonstrate that the enhanced absorption peak of the sphere is geometrically tunable over the entire visible range.

physics.optics↗

arXiv2006

Coherent Light Scattering from Semicontinuous Silver Nanoshells Near the Percolation Threshold

We report on measurements of visible extinction spectra of semicontinuous silver nanoshells grown on colloidal silica spheres. We find that thin, fractal shells below the percolation threshold exhibit geometrically tunable plasmon resonances. A modified scaling theory approach is used to model the dielectric response of such shells, which is then utilized to obtain the extinction cross section in a retarded Mie scattering formalism. We show that such spherical resonators support unique plasmon dynamics: in the visible there is a new regime of coherently driven cluster-localized plasmons, while crossover to homogeneous response in the infrared predicts a delocalized shell plasmon.

physics.optics↗

arXiv2004

Surface plasmon polariton propagation around bends at a metal-dielectric interface

We analyze theoretically the propagation of surface plasmon polaritons about a metallic corner with a finite bend radius, using a one-dimensional model analogous to the scattering from a finite-depth potential well. We obtain expressions for the energy reflection and transmission coefficients in the short wavelength limit, as well as an upper bound for the transmittance. In certain cases we find that propagation on non-planar interfaces may result in lower losses than on flat surfaces, contrary to expectation. In addition, we also find that the maximum transmittance depends non-monotonously on the bend radius, allowing increased transmission with decreasing radius.

physics.optics↗