Surface Plasmon Polariton Propagation at the Interface of a Metal and an Ambichiral Nanostructured Medium

The propagation of a surface plasmon polariton wave at the interface of a metal and an ambichiral nanostructured medium was theoretically investigated in the Kretschmann configuration using transfer matrix method. The dependence of optical absorption linear polarization on structural parameters was reported. The results were compared with those obtained from the interface of a metal and a chiral dielectric medium as a reference structure. We found that multiple plasmon modes are excited at the interface of metal and ambichiral dielectric medium. Our calculations revealed that there exist five plasmon modes for chiral, trigonal, and tetragonal structures; three plasmon modes for pentagonal structure; two plasmon modes for hexagonal structure; and one plasmon mode for dodecagonal structure that propagate with different phase speeds. The obtained results showed that only one plasmon mode occurs at all pitches, while other modes exist at some of the pitches of anisotropic chiral and ambichiral dielectric mediums. The time-averaged Poynting vector versus the thickness of metal film confirmed that the energy of photons of incident light is transferred to surface plasmon polariton quasiparticles and the surface plasmon polariton wave is localized at the interface of metal and ambichiral dielectric medium.     

Surface Plasmon Polariton Excitation in Metallic Layer Via Surface Relief Gratings in Photoactive Polymer Studied by the Finite-Difference Time-Domain Method

We performed numerical investigations of surface plasmon excitation and propagation in structures made of a photochromic polymer layer deposited over a metal surface using the finite-difference time-domain method. We investigated the process of light coupling into surface plasmon polariton excitation using surface relief gratings formed on the top of a polymer layer and compared it with the coupling via rectangular ridges grating made directly in the metal layer. We also performed preliminary studies on the influence of refractive index change of photochromic polymer on surface plasmon polariton propagation conditions.     

Femtosecond Pulse Propagation through Au and Ag Nanowires

Plasmonics - We examine the pulse reshaping of femtosecond pulses propagating through the fundamental surface plasmon polariton mode guided along Au and Ag nanowires. It is observed that the...     

Controllable Mode Hybridization and Interaction Within a Plasmonic Cavity Formed by Two Bimetallic Gratings

We theoretically study mode hybridization and interaction among surface plasmon polariton Bloch wave mode, Fabry–Perot cavity mode, and waveguide mode within a plasmonic cavity composed by two parallel planar bimetallic gratings. Four hybridized modes result from mode hybridization between surface plasmon polariton Bloch wave modes on the two gratings are observed. By changing the dielectric environment, mode hybridization behavior can be manipulated. Importantly, waveguide-plasmon polariton mode due to hybridization between grating supported surface plasmon polariton Bloch wave mode and cavity supported waveguide mode is observed. We demonstrate that surface plasmon polariton Bloch wave mode and Fabry–Perot cavity mode with the same mode symmetry can interact by presenting an anticrossing behavior, which can be controlled by laterally shifting one grating with respect to the other that causes a phase difference shift of the two involving modes. The proposed plasmonic cavity offers potentials for subwavelength lithography, tunable plasmonic filter, and controllable light-matter interaction.     

Characteristics of Plasmonic at a Metal/Chiral Sculptured Thin Film Interface

The propagation of surface plasmon polariton at an interface of metallic thin film and chiral sculptured thin film theoretically has been investigated using the transfer matrix method in the Kretschman configuration. The optical absorption of structure as a function of polar incident angle for linear polarization P and S has been calculated at different structural parameters. The results show that exist multiple plasmon peaks for P polarization, while there are the weak plasmon peaks when incident of light is S-polarized plane wave.     

Modelling of Polarization-Dependent Loss in Plasmonic Nanowire Waveguides

We have investigated the potential of using gold nanowires embedded in a dielectric cladding environment as polarization-independent long-range surface plasmon polariton waveguides at telecom wavelengths. We performed finite-element analysis on various symmetric and close-to-symmetric cross-sectional geometries and evaluated the effects of cladding thickness on the propagation and coupling loss. The calculations confirm that fabrication of polarization-independent waveguides with reasonable tolerances is feasible and that straight-waveguide insertion losses around 1.5 dB for short (0.5 mm) devices can be realized when coupling to and from conventional dielectric waveguide geometries.     

An Efficient Large-Area Grating Coupler for Surface Plasmon Polaritons

We report the design, fabrication, and characterization of a periodic grating of shallow rectangular grooves in a metallic film with the goal of maximizing the coupling efficiency of an extended plane wave (PW) of visible or near-infrared light into a single surface plasmon polariton (SPP) mode on a flat metal surface. A PW-to-SPP power conversion factor >45% is demonstrated at a wavelength of 780?nm, which exceeds by an order of magnitude the experimental performance of SPP grating couplers reported to date at any wavelength. Conversion efficiency is maximized by matching the dissipative SPP losses along the grating surface to the local coupling strength. This critical coupling condition is experimentally achieved by tailoring the groove depth and width using a focused ion beam.     

Nanostructuring of Continuous Gold Film by Laser Radiation Under Surface Plasmon Polariton Resonance Conditions

The physical mechanisms of metallic nanoparticles formation by laser technology were studied. The system air/Au film/glass was irradiated by laser at the conditions of surface plasmon resonance. A surface electromagnetic wave was excited in Kretchmann configuration by the fundamental and second harmonics of the Q-switched YAG/Nd⁺³ laser with pulse power density close to the threshold of melting. Nanostructuring of Au film was observed only for the second harmonic (λ = 0.532 μm) irradiation at the surface plasmon polariton resonance (SPR) conditions. Estimations were done using the interference model of the differently directed plasmon polariton waves excited by a surface electromagnetic wave on the metal surface. It was shown that a regular pattern of locally heated spots can be formed in a metallic film by pulsed laser irradiation. The spatial distribution of this pattern is close to the period of interference. The observed effect of laser nanofragmentation is explained by the self-organization of plasmon polariton subsystem in the process of Au nanoparticles formation at high laser intensity levels. These methods open new possibilities for nanostructured surfaces formation utilizing simple self-organization processes.     

Surface Plasmon Polariton Modes at Interface of a Metal and an Ambichiral Sculptured Thin Film

The excitation of surface plasmon polariton (SPP) at interface of a metal and an ambichiral sculptured thin film was theoretically investigated in the Kretschmann configuration using the transfer matrix method. The dependence of SPP modes for a P polarization plane wave on the incident angle of light and the angle of rise of nanocolumns of ambichiral dielectric medium was reported. We found that multiple SPP modes are excited at the interface of metal and ambichiral dielectric medium. The results of phase speed as a function of pitch showed only that a SPP mode can be excited at all pitches.     

Anticrossing Behavior of Surface Plasmon Polariton Dispersions in Metal-Insulator-Metal Structures

The anticrossing behavior of dispersion curves of the surface plasmon polaritons supported by metal-insulator-metal structures are studied experimentally and theoretically. Samples consisting of a poly(methyl methacrylate) layer sandwiched by Ag films are prepared and their angle- and wavelength-scan attenuated total reflection spectra are measured. From an analysis of the angle-scan spectrum, the coupled-mode nature of the surface plasmon polariton modes is suggested. The dispersion relations obtained from the wavelength-scan spectra exhibit clearly the anticrossing behavior that arises from the coupling of the modes. The experimental dispersion relations are in good agreement with theoretical ones.     

Scattering of Surface Plasmon by Nano-probe. Influence of the Local Field Inhomogeneity

The surface plasmon polariton scattering by nanoparticle was considered in the frame of approach based on the effective susceptibility concept. The main feature of the approach is taking into account the inhomogeneity of the local field at the nanoparticle. The inhomogeneity strongly influences on the effective susceptibility of the particle formation. The approach allowed to explain the nonmonotonic behavior of scattered field intensity at the detector placed in far zone on the distance between the particle and a surface obtained experimentally in reported earlier by other authors.     

Design,Analysis, and Characterization of Designer Surface Plasmon Polariton-Based Dual-Band Antenna

This paper reports development, design, and analysis of designer (or spoof) surface plasmon polariton-based feeding configuration to excite a dual-band antenna. As an example, a planar transverse electric and magnetic horn antenna is designed and fed by the proposed transition structure. Designer surface plasmon polariton modes are supported by a metal surface at microwave frequency when it is corrugated with periodical grooves. An efficient transition for converting quasi-transverse electric and magnetic waves of microstrip line into spoof surface plasmon polariton (SSPP) waves has been designed in microwave frequency range using periodically corrugated metal strip. SSPP wave is confined at the teeth part of the corrugation. Simulated and measured reflection and transmission characteristics are in good agreement. The spoof SPP-fed dual-band antenna is designed, fabricated, and characterized in microwave anechoic chamber and measured results are coincident with simulated results.     

Unidirectional Surface Plasmon Polariton Excitation on Single Slit with Oblique Backside Illumination

We have theoretically investigated the unidirectional surface plasmon polariton (SPP) excitation on single slits with oblique backside illumination. An aperture diffraction method is devised, from which the conditions of slit width and beam illumination angle for the unidirectional SPP excitation are formulated analytically. The derived unidirectional conditions are validated with vectorial electromagnetic simulation using the rigorous coupled wave analysis.     

A Polarization Filter Based on Photonic Crystal Fiber with Asymmetry Around Gold-Coated Holes

We propose a modified design for a photonic crystal fiber (PCF) filter based on surface plasmon resonance(SPR). The air holes are arrayed in rectangular lattices, while the size and the pitches of holes around the gold-coated holes are different. That can separate the x-polarization and y-polarization of second-order surface plasmon polariton (SPP). The resonance strength of the surface plasmon mode and import of structural parameters of the PCF on the filter characteristics are studied through using the finite element method (FEM). Numerical simulations demonstrate that the thickness of the gold layer, the gold-coated or gold-filled, and the asymmetry around the gold-coated holes have a great effect on the filter characteristics. It is certain to obtain a resonance strength as high as 873 and 771.5 dB/cm at the communication wavelength of 1050 and 1310 nm in x-polarization by adjusting the size and the place of the gold-coated holes, while the loss is extremely low in y-polarization.     

Engineering the Optical Response of the Novel Plasmonic Binary Nanohole Array

The phenomenon of extraordinary optical transmission (EOT) due to its advantages has been considered by researchers in various applications, and in recent years, many efforts have been made to engineer these structures to get the best possible response for desired applications. In this work, the optical properties of novel binary gold nanohole arrays are investigated theoretically. We engineered the optical response of the system by adjusting the ratio of contribution of surface plasmon polariton (SPP) to localized surface plasmon resonance (LSPR) through the manipulation of the geometrical properties. The changes in the topology of this nanohole array affected the intensity and the wavelength of transmission peaks. The sensitivity of the optical response to the refractive index was also investigated. The designed structure is a good candidate for use as a polarization-independent optical label-free sensor.

     

A Near-field Nanosource Based on Surface Plasmon Bragg Reflectors and Nanocavity

We demonstrate a type of confined nanosource based on surface plasmon band-gap structure consisting of a nanocavity surrounded by grooves. A single, localized, and non-radiating central peak is obtained and can be used as a nanosource. The characteristics of the surface plasmon polariton (SPP) field in the vicinity of the structures with different geometrical parameters are investigated experimentally. A confined central peak is obtained in the nanocavity. The full width at half maximum of the central peak is beyond the diffraction limit and changes little during 600 nm distance away from the sample surface. With the modifications of the geometrical parameters, the central peak intensity can be enhanced and the sidelobes can be suppressed. The physical origin of the enhancement and the surface-sensitivity is explored theoretically. These phenomena demonstrate the abilities of the structures to collect the electromagnetic field and to tailor the SPP field profile. This type of SPP-based nanosource is promising to be applied in near-field imaging, data storage, optical manipulation, and localized spectrum excitation, and has potential applications in nano-photonics devices based on SPPs.     

Surface Plasmon Polariton Waveguide by Bottom and Top of Graphene

Semiconductor surface plasmon polariton (SPP) waveguide has unique optical properties and compatibility with existing integrated circuit manufacturing technology; thus, SPP devices of semiconductor materials have wide application potential. In this study, a new integrated graphene SPP waveguide is designed using the bottom and top roles of graphene. Moreover, a T waveguide structure is designed by InGaAs of semiconductor gain, with rectangular GaAs material on both sides. The structure adopts light to stimulate the SPP, where its local area is enhanced by the interaction between two interface layers and a semiconductor gain and where its frequency can be adjusted by the thickness of the graphene. Characteristic analysis reveals the coupling between the T semiconductor gain and the SPP mode. The propagation distance of the waveguide can reach 75 cm, the effective mode field is approximately 0.0951λ ², the minimum of gain threshold is approximately 2992.7 cm^?1, and the quality factor (FOM) can reach 180. The waveguide structure which provides stronger localization can be compatible with several optical and electronic nanoscale components. That means, it can provide light for surface plasmon circuit and also can provide a great development in the low-threshold nanolaser.     

Plasmon-Induced Transparency in a Surface Plasmon Polariton Waveguide with a Right-Angled Slot and Rectangle Cavity

Plasmonics - The phenomenon of plasmon-induced transparency (PIT) is realized a in surface plasmon polariton waveguide at near-infrared frequencies. The right-angled slot and rectangle cavity...     

Coupling Behaviors of Surface Plasmon Polariton and Localized Surface Plasmon with an InGaN/GaN Quantum Well

Plasmonics - Surface plasmon (SP) coupling behaviors of an InGaN/GaN quantum well (QW) with surface plasmon polariton (SPP) induced on a smooth Ag-film/GaN interface and localized surface plasmon...     

Gold Nanowire and Nanorod Plasmonic Mechanisms for Increasing Ultra-Thin Organic Photovoltaic Active Layer Absorption

We theoretically investigate the effect of incorporating gold cylindrical- and ellipsoidal-shaped nanowires and gold nanorods situated centrally within the active layer of organic bulk-heterojunction photovoltaic devices, on the optical absorption performance using finite element electromagnetic simulations. Gold cylindrical nanowire-embedded devices show increased active layer absorption enhancement with increasing radius; however, this effect decreases with the introduction of a polystyrene dielectric capping layer around the nanowires. Active layer absorption, with respect to changes in the orientation, aspect ratio, periodicity, and spacing between ellipsoidal nanowires were optimized. A maximum absorption enhancement weighted by AM 1.5 solar spectrum of 17 % is predicted for gold ellipsoidal nanowires of aspect ratio of 1.167 with in-plane horizontal orientation and arranged with periodicity of 35 nm within a 30-nm thin active layer. We attribute this enhancement primarily to interparticle electromagnetic coupling between adjacent nanowires, where, a maximum spatial and spectral overlap of the electromagnetic field with the absorption band of the active layer material is achieved. This effect increases with decreasing aspect ratio as well as decreasing periodicity with a trade-off observed between nanowire packing density and the active layer absorption enhancement. For gold nanorod-embedded organic photovoltaic devices, the inter-particle electromagnetic coupling effects are weaker and longitudinal surface–plasmon resonances supported by the nanorods are more pronounced. However, since the longitudinal surface–plasmon resonances occur at wavelengths greater than the absorption edge of the photovoltaic active layer, a mere 3.4 % increase in absorption enhancement is achieved for the photovoltaic device incorporating gold nanorods with aspect ratio of 1.167 and periodicity of 35 nm.