Combination Of Plasmonics Research Articles

Nonvolatile Plasmonics Based on Optically Reprogrammable Phase Change Materials

Here, a new platform for a realization of novel nonvolatile optical switching devices was proposed that takes an advantage of high field confinement provided by plasmonics and multi-state programming capabilities of chalcogenide phase change materials. A high reduction in the overall energy consumption consists of a high field enhancement provided by plasmonic that allow to lower the switching energies and implementation of phase change materials that allow to operate under a zero-static power consumption. A combination of plasmonics and phase change materials provide additionally an essential improvement in terms of a switching time, attenuation contrast and possibility to perform a phase shift with the wide bandgap phase change materials. In most of the all-optical switching photonic devices, a switching mechanism is realized optically through heating of phase change materials. Here, two stage heating process is proposed that is based on the absorption of light by phase change materials itself, and a heat transfer from the metal stripe under an absorption of light by a metal. Thus, compared to any other previously presented optical switches, even a wide bandgap phase change materials that show zero absorption of light can be implemented in the proposed structure. The proposed plasmonic waveguide arrangement is extremely sensitive to any changes of the phase change material properties, thus, even a minor change of temperature provides an essential change in the transmitted light.

Near-Perfect Absorbing Copper Metamaterial for Solar Fuel Generation.

Metamaterials are a new class of artificial materials that can achieve electromagnetic properties that do not occur naturally, and as such they can also be a new class of photocatalytic structures. We show that metal-based catalysts can achieve electromagnetic field amplification and broadband absorption by decoupling optical properties from the material composition as exemplified with a ZnO/Cu metamaterial surface comprising periodically arranged nanocubes. Through refractive index engineering close to the index of air, the metamaterial exhibits near-perfect 98% absorption. The combination of plasmonics and broadband absorption elevates the weak electric field intensities across the nonplasmonic absorption range. This feedback between optical excitation and plasmonic excitation dramatically enhances light-to-dark catalytic rates by up to a factor of 181 times, compared to a 3 times photoenhancement of ZnO/Cu nanoparticles or films, and with angular invariance. These results show that metamaterial catalysts can act as a singular light harvesting device that substantially enhances photocatalysis of important reactions.

Methods for tuning plasmonic and photonic optical resonances in high surface area porous electrodes

Surface plasmons have found a wide range of applications in plasmonic and nanophotonic devices. The combination of plasmonics with three-dimensional photonic crystals has enormous potential for the efficient localization of light in high surface area photoelectrodes. However, the metals traditionally used for plasmonics are difficult to form into three-dimensional periodic structures and have limited optical penetration depth at operational frequencies, which limits their use in nanofabricated photonic crystal devices. The recent decade has seen an expansion of the plasmonic material portfolio into conducting ceramics, driven by their potential for improved stability, and their conformal growth via atomic layer deposition has been established. In this work, we have created three-dimensional photonic crystals with an ultrathin plasmonic titanium nitride coating that preserves photonic activity. Plasmonic titanium nitride enhances optical fields within the photonic electrode while maintaining sufficient light penetration. Additionally, we show that post-growth annealing can tune the plasmonic resonance of titanium nitride to overlap with the photonic resonance, potentially enabling coupled-phenomena applications for these three-dimensional nanophotonic systems. Through characterization of the tuning knobs of bead size, deposition temperature and cycle count, and annealing conditions, we can create an electrically- and plasmonically-active photonic crystal as-desired for a particular application of choice.

Plasmon-Mediated Surface Functionalization: New Horizons for the Control of Surface Chemistry on the Nanoscale

The combination of plasmonics and surface chemistry is a fast growing field of research, with promising prospects for a wide range of applications, including analytical chemistry, sensing, photocat...

Dual band metamaterial absorber: Combination of plasmon and Mie resonances

A dual band metamaterial absorber composed of dielectric and metallic atoms with high symmetry was numerically designed and experimentally verified. Due to simultaneously generated electric and magnetic resonances of both plasmon and Mie resonators, two absorption peaks with near unity absorptivity were obtained at 9.45 and 9.80 GHz. The loss of the electromagnetic wave at the first resonance frequency was mainly caused by ohmic loss based on plasmon resonance. For the second absorption peak resonance frequency, the incident wave was trapped inside the dielectric cube and the main loss of the electromagnetic wave was caused by dielectric loss based on Mie resonance. Most of the proposed dual band metamaterial absorbers were sensitive to the polarization direction hindering its potential applications in scientific and technological areas. Combing both plasmon and Mie resonances provides a new and simple way to build dual band isotropic metamaterial perfect absorbers eliminating polarization effect.

One dimensional photonic crystal as an efficient tool for in-vivo optical sensing of neural activity

In this paper, we recorded optically the neural/neuromuscular activity of alive worm via phase-sensitive measurement while stimulating it optically using infrared laser. By supporting Tamm plasmon mode, our fabricated multilayer structure of Glass/(TiO2/SiO2)12/Au was used as a sensing platform. By fixing an earth worm to the gold side of the structure and using open optic measurements, the amplitude ratio (Ψ) and phase shift (Δ) of reflections under s- and p-polarized incident lights have been recorded for different frequencies and pulse duration of IR laser. By increasing the pulse duration to 17 m s, Δ and Ψ values of Tamm Plasmon Polariton resonance for different frequencies have been splitted considerably in a regular trend. We hope that the combination of plasmonics and Tamm plasmon mode can open new insights into non-invasive neural/neuromusular stimulation and recording.

Multifunctional Sn- and Fe-Codoped In2O3 Colloidal Nanocrystals: Plasmonics and Magnetism.

We prepared Fe- and Sn-codoped colloidal In2O3 nanocrystals (∼6 nm). Sn doping provides free electrons in the conduction band, originating localized surface plasmon resonance (LSPR) and electrical conductivity. The LSPR band can be tuned between 2000 and >3000 nm, depending on the extent and kind of dopant ions. Fe doping, on the other hand, provides unpaired electrons, resulting in weak ferromagnetism at room temperature. Fe doping shifts the LSPR band of 10% Sn-doped In2O3 nanocrystals to a longer wavelength along with a reduction in intensity, suggesting trapping of charge carriers around the dopant centers, whereas Sn doping increases the magnetization of 10% Fe-doped In2O3 nanocrystals, probably because of the free electron mediated interactions between distant magnetic ions. The combination of plasmonics and magnetism, in addition to electronic conductivity and visible-light transparency, is a unique feature of our colloidal codoped nanocrystals.

Switching using PT symmetry in plasmonic systems: positive role of the losses

We analyze the operation of 2 × 2 switches composed of two coupled waveguides operating on the basis of parity-time (PT) symmetry: the two waveguides differ through their gain or loss factors and not through the real part of their propagation constant. Plasmonics constitutes a preferred application for such systems, since combination of plasmonics with gain is increasingly mastered. The exact PT-symmetric case (gain and loss of identical absolute value) is considered as well as various unbalanced cases, thanks to their respective switching diagrams. Although perfect signal-conserving cross and bar states are not always possible in the latter cases, they can nevertheless form the basis of very good switches if precise design rules are followed. We draw from the analysis what the optimal configurations are in terms of, e.g., guide gain or gain-length product to operate the switch. Many analytical or semi-analytical results are pointed out. A practical example based on the coupling of a long-range surface-plasmon-polariton and a polymeric waveguide having gain is provided.