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Algorithms for modeling the spatial dispersion in epsilon-near-zero media are needed in designing compact nonlinear-optical devices. Improved finite-difference time-domain modeling of a metallic thin film shows that spatial dispersion increases the group velocity of the surface mode at an epsilon-near-zero frequency. [ABSTRACT FROM AUTHOR]

In this work we demonstrate the fabrication protocol of 2D-magnetoplasmonic crystals consisting of permalloy column arrays. Dependences of morphological, magnetic, optical, and magneto-optical properties of 2D-magnetoplasmonic crystals on the e-beam exposition dose are studied. Proposed protocol is suitable for the fabrication of 2D-structures with controllable dimensions and morphology of individual columns having substantial potential for applications as sensitive magnetic field probes. [ABSTRACT FROM AUTHOR]

The possibilities of practical implementation of physical approaches to the design of metal–dielectric photonic crystal systems based on opals, which allow controlling the propagation of electromagnetic waves, are shown. The implemented approaches are based on the effects of excitation of surface plasmon-polaritons capable of propagating along the metal–dielectric interface in plasmonic-photonic layered heterostructures, and modification of the photonic-energy structure of the nanocomposite as a result of dispersion of silver in the opal matrix. Experimental results are presented indicating the occurrence of extraordinary transmission and absorption of light in plasmonic-photonic heterostructures, as well as the asymmetric shape of curves in the reflection spectra of nanocomposites, which is associated with the Fano resonance. [ABSTRACT FROM AUTHOR]

The results of study of the behavior of surface plasmon polaritons in the layered structure of a VO2‒SiO2-graphene-based hyperbolic metasurface under the influence of an external magnetic field before and at the beginning of the phase transition of vanadium dioxide are presented. As a result of calculations, it is shown how the isofrequency contour of surface plasmons changes taking into account the different direction of the external magnetic field. It is also shown how an external magnetic field affects the direction of static magnetization caused by the inverse Faraday effect. This work can offer additional ways to control the behavior of surface plasmons, as well as become the basis for the study of new self-adjusting structures. [ABSTRACT FROM AUTHOR]

In this paper, features of generation of two types of surface plasmon-polaritons (SPPs) in optical anisotropic hyperbolic metamaterials formed by a periodic lattice of metal nanocylinders embedded in a dielectric matrix are considered. The dependencies of the group velocity and the penetration depth inside metamaterial of the generated plasmon-polaritons on filling ratio are established and analyzed. Based on the effective medium theory, the surface plasmon-polaritons generation at interface of hyperbolic metamaterials is analytically calculated and discussed. [ABSTRACT FROM AUTHOR]

One-dimensional femtosecond laser-induced periodic surface structures (LIPSS) were formed on amorphous silicon (a-Si) films doped with phosphorus (n-a-Si) and boron (p-a-Si). The formed LIPSS ridges are directed orthogonally to the laser polarization and their period decreases from 1.1 ± 0.1 µm to 0.84 ± 0.07 µm for p-a-Si and from 1.06 ± 0.03 to 0.98 ± 0.01 for n-a-Si when the number of laser pulses per unit area increases from 30 to 120. Raman spectra analysis indicated nonuniform nanocrystallization of the irradiated films, which have a composite structure of amorphous matrix containing nanocrystalline Si phase with volume fraction decreasing with depth from ~80 to ~40% for p-a-Si and from ~20 to ~10% for n-a-Si. Observed in plane conductivity anisotropy of up to 1 order for irradiated films may be explained by the LIPSS depolarizing effect, excessive ablation of the film between LIPSS ridges, as well as anisotropic crystalline phase distribution within the film. [ABSTRACT FROM AUTHOR]

Femtosecond laser-modified amorphous silicon (a-Si) films with optical and electrical anisotropy have perspective polarization-sensitive applications in optics, photovoltaics, and sensors. We demonstrate the formation of one-dimensional femtosecond laser-induced periodic surface structures (LIPSS) on the surface of phosphorus- (n-a-Si) and boron-doped (p-a-Si) amorphous silicon films. The LIPSS are orthogonal to the laser polarization, and their period decreases from 1.1 ± 0.1 µm to 0.84 ± 0.07 µm for p-a-Si and from 1.06 ± 0.03 to 0.98 ± 0.01 for n-a-Si when the number of laser pulses per unit area increases from 30 to 120. Raman spectra analysis indicates nonuniform nanocrystallization of the irradiated films, with the nanocrystalline Si phase volume fraction decreasing with depth from ~80 to ~40% for p-a-Si and from ~20 to ~10% for n-a-Si. LIPSS' depolarizing effect, excessive ablation of the film between LIPSS ridges, as well as anisotropic crystalline phase distribution within the film lead to the emergence of conductivity anisotropy of up to 1 order for irradiated films. Current–voltage characteristic nonlinearity observed for modified p-a-Si samples may be associated with the presence of both the crystalline and amorphous phases, resulting in the formation of potential barriers for the in-plane carrier transport and Schottky barriers at the electric contacts. [ABSTRACT FROM AUTHOR]

A plasmonic refractive index sensor including a metal–insulator-metal (MIM) waveguide with four teeth is proposed. Transmittance (T), sensitivity (S), and figure of merit (FOM) were investigated numerically and analyzed via the finite difference time domain method (FDTD). The simulation results show the generation of double Fano resonances in the system that the resonance wavelength and the resonance line-shapes can be adjusted by changing the geometry of the device. This device is optimized by changing the length of the teeth and their distance from each other. As a result, the maximum sensitivity and FOM values are 1078 nm/RIU and 1.54 × 106, respectively. Due to proper performance and adjustable Fano resonance points, this structure is significant for fabricating sensitive refractive index sensor and plasmonic bandpass filter. [ABSTRACT FROM AUTHOR]

The paper reports on the study of optical phenomena peculiarities in metal-dielectric nanocomposite materials based on opal matrices caused by the excitation and propagation of surface plasmon-polaritons along the metal-dielectric interface. It is shown that two types of surface plasmon polaritons (‘bright’ and ‘dark’) can occur in the studied structures, which manifests itself in the established anomalies of light transmission and absorption.

Two types of novel graphene-based components, namely, filters and electro-optical switches in guided wave configuration are suggested and analysed. The filters differ from the known ones with collinear orientation of the input and output waveguides by geometry and symmetry. The components consist of a circular graphene disk and two nanoribbons oriented at 90° to each other in the plane of the graphene layer. The graphene elements are placed on a dielectric substrate. We show that change in symmetry leads to a drastic change in the properties of the components. The physical principle of the devices is based on the dipole, quadrupole and hexapole resonances in the graphene disk which define stop-band, pass-band and stop-band frequency characteristics, respectively. A combination of stop-band and pass-band filter properties by shifing the electronic Fermi level allows one to design a switch. Numerical simulations show that the suggested components have very small dimensions, good characteristics and provide a dynamic control of their central frequency via electrostatic gating.

Achieving robust propagation and guiding of electromagnetic waves through complex and disordered structures is a major goal of modern photonics research, for both classical and quantum applications. Although the realization of backscattering-free and disorder-immune guided waves has recently become possible through various photonic schemes inspired by topological insulators in condensed matter physics, the interaction between such topologically protected guided waves and free-space propagating waves remains mostly unexplored, especially in the context of scattering systems. Here, we theoretically demonstrate that free-space propagating plane waves can be efficiently coupled into topological one-way surface waves, which can seamlessly flow around sharp corners and electrically large barriers and release their energy back into free space in the form of leaky-wave radiation. We exploit this physical mechanism to realize topologically protected wave-rerouting around an electrically large impenetrable object of complex shape, with transmission efficiency exceeding 90%, over a relatively broad bandwidth. The proposed topological wave-rerouting scheme is based on a stratified structure composed of a topologically nontrivial magnetized plasmonic material coated by a suitable isotropic layer. Our results may open a new avenue in the field of topological photonics and electromagnetics, for applications that require engineered interactions between guided waves and free-space propagating waves, including for complex beam-routing systems and advanced stealth technology. More generally, our work may pave the way for robust defect/damage-immune scattering and radiating systems.

Abstract An idea of the surface plasmon resonance (SPR) has been utilized for the design of highly sensitive sensors based on the wagon-wheel fiber technology. Such sensors are sensitive to changes in the refractive index of sample analyte. In this study, a three-strut wagon-wheel structure, coated with the gold layer of nano-sized thickness, has been proposed as the SPR sensor. Finite element method is employed to simulate and tune the proposed SPR’s design, which leads to a highly sensitive and multichannel plasmonic sensor with the ability for a dual reading on a single analyte or simultaneous identification of two analytes. In this design, suitable thickness values for the gold layer and core struts are determined. Sensitivities of the detector due to the first resonance peak, second resonance peak, and the difference in resonance peaks are calculated to be 1120 nm/RIU, 1540 nm/RIU, and 420 nm/RIU, respectively, when analytes are placed in all three channels of the fiber. Sensitivity of the detector with respect to the second resonant peak for analyte in Channels 2 and 3 is also found to be 1252 nm/RIU when Channel 1 is filled with the reference. The sensitivity and resolution of the sensor increase as the refractive index of the analyte increases by almost a linear proportion. If the sensor is utilized to detect the difference in two peaks, it would substantially reduce the noise, and the best result is expected. The thicknesses of the struts and the gold layer are proper parameters to be tuned in designing the detector.

An experimental study of the optical properties of two types of metal–dielectric composites based on opal matrices has been carried out: (1) layered structures, obtained by successive deposition of metal and dielectric films on a monolayer of opal globules, where anomalous transmission and absorption of light was found due to the excitation of surface plasmon polaritons of various types; (2) "massive" opal samples, into which the metal was introduced by the method of electrothermal diffusion, where an asymmetric shape of Bragg resonance curves was observed, due to the Fano resonance. [ABSTRACT FROM AUTHOR]

Two types of novel graphene-based components, namely, filters and electro-optical switches in guided wave configuration are suggested and analysed. The filters differ from the known ones with collinear orientation of the input and output waveguides by geometry and symmetry. The components consist of a circular graphene disk and two nanoribbons oriented at 90° to each other in the plane of the graphene layer. The graphene elements are placed on a dielectric substrate. We show that change in symmetry leads to a drastic change in the properties of the components. The physical principle of the devices is based on the dipole, quadrupole and hexapole resonances in the graphene disk which define stop-band, pass-band and stop-band frequency characteristics, respectively. A combination of stop-band and pass-band filter properties by shifing the electronic Fermi level allows one to design a switch. Numerical simulations show that the suggested components have very small dimensions, good characteristics and provide a dynamic control of their central frequency via electrostatic gating. [ABSTRACT FROM AUTHOR]

Recent experimental results on formation of ordered surface nanostructures of hexagonal symmetry on metals under the action of a series of scanned doubled collinear femtosecond pulses of orthogonal polarization and variable time delay are analyzed. It is demonstrated that the appearance of structures is related to the formation of a dynamic grating by the first pulse and excitation of two pairs of surface plasmon–polaritons by the second pulse in directions symmetric with respect to its vector of polarization and forming an angle of π/3 with each other. This leads to the formation of corresponding dynamic gratings and fourfold degeneracy of the first grating. Three dynamic gratings symmetric with respect to the surface normal form a residual surface relief of hexagonal symmetry that can be observed experimentally. [ABSTRACT FROM AUTHOR]

In the presence of a DC magnetic field, the conductivity of graphene acquires tensor character with antisymmetric nondiagonal elements. This property can be used for creation of nonreciprocal elements in THz region. In this work, we propose and investigate two 4‐port circulators with a planar structure. They are composed of a graphene layer placed on a dielectric substrate. The orientation of the external DC magnetic field is normal to the graphene layer. The graphene geometry of the first circulator presents four strips with surface plasmon‐polariton waves. The strips are connected symmetrically to the magnetized central region such that the whole structure possesses 4‐fold rotational symmetry. The operating region of the circulator at low frequency end is limited by the cyclotron frequency of magnetized graphene and at high frequencies by the appearance of the higher mode in the graphene waveguidings structures. Using numerical calculus, we give an example of the circulator project with the following scattering parameters: S11 is better than −10 dB, the isolation level is less than −15 dB, insertion loss is better than −3 dB in the (1.6 ÷ 2.65) THz region with the bandwidth of 44%. The second four‐port circulator has a linear geometry with lower symmetry where the number of ports can be easily increased. It has the bandwidth also of about 44%. In both cases, the DC magnetic field is 1.5 T and the Fermi energy of graphene μc = 0.15 eV. [ABSTRACT FROM AUTHOR]

Theory of five kinds of layered structure THz waveguides is presented. In these waveguides, the modified and hybrid THz surface plasmon-polaritons (SPPs) are researched in detail. On these modes, the effects of material in each layer are discussed. The anti-resonant reflecting mechanism is also discussed in these waveguides. The mode characteristics of both TM mode and TE mode are analyzed for guiding TM mode with low loss and TE modes with huge loss in one waveguide: the TE modes filter application is put forward. The mode characteristics for one waveguide have useful sensor applications: for TE1 mode, we find that the low cut-off frequency has a sensitivity (S) to the refractive index of the dielectric slab. The highest S can be 666.7 GHz/RIU when n2 = 1.5, w = 0 and t = 0.1 mm. We believe these results are very useful for designing practical THz devices for SPPs, filter and sensor applications. [ABSTRACT FROM AUTHOR]

An idea of the surface plasmon resonance (SPR) has been utilized for the design of highly sensitive sensors based on the wagon-wheel fiber technology. Such sensors are sensitive to changes in the refractive index of sample analyte. In this study, a three-strut wagon-wheel structure, coated with the gold layer of nano-sized thickness, has been proposed as the SPR sensor. Finite element method is employed to simulate and tune the proposed SPR's design, which leads to a highly sensitive and multichannel plasmonic sensor with the ability for a dual reading on a single analyte or simultaneous identification of two analytes. In this design, suitable thickness values for the gold layer and core struts are determined. Sensitivities of the detector due to the first resonance peak, second resonance peak, and the difference in resonance peaks are calculated to be 1120 nm/RIU, 1540 nm/RIU, and 420 nm/RIU, respectively, when analytes are placed in all three channels of the fiber. Sensitivity of the detector with respect to the second resonant peak for analyte in Channels 2 and 3 is also found to be 1252 nm/RIU when Channel 1 is filled with the reference. The sensitivity and resolution of the sensor increase as the refractive index of the analyte increases by almost a linear proportion. If the sensor is utilized to detect the difference in two peaks, it would substantially reduce the noise, and the best result is expected. The thicknesses of the struts and the gold layer are proper parameters to be tuned in designing the detector. [ABSTRACT FROM AUTHOR]

One-dimensional periodic surface structures were formed by femtosecond laser irradiation of amorphous hydrogenated silicon (a-Si:H) films. The a-Si:H laser processing conditions influence on the periodic relief formation as well as correlation of irradiated surfaces structural properties with their electrophysical properties were investigated. The surface structures with the period of 0.88 and 1.12 μm were fabricated at the laser wavelength of 1.25 μm and laser pulse number of 30 and 750, respectively. The orientation of the surface structure is defined by the laser polarization and depends on the concentration of nonequilibrium carriers excited by the femtosecond laser pulses in the near-surface region of the film, which affects a mode of the excited surface electromagnetic wave which is responsible for the periodic relief formation. Femtosecond laser irradiation increases the a-Si:H films conductivity by 3 to 4 orders of magnitude, up to 1.2 × 10−5 S∙cm, due to formation of Si nanocrystalline phase with the volume fraction from 17 to 28%. Dark conductivity and photoconductivity anisotropy, observed in the irradiated a-Si:H films is explained by a depolarizing effect inside periodic microscale relief, nonuniform crystalline Si phase distribution, as well as different carrier mobility and lifetime in plane of the studied samples along and perpendicular to the laser-induced periodic surface structures orientation, that was confirmed by the measured photoconductivity and absorption coefficient spectra.

We demonstrate effective, up to 30%, reflection of the surface plasmon-polariton wave (SPP) from a nanogroove made on Ag film surface. The use of SPP reflection from a nanogroove having a shape of parabola helps to realize a new element in nanoplasmonics—parabolic SPP mirror. It was found that the mirror allows focusing of the SPP into a diffraction-limited spot with a lateral size of about λSPP (λSPP = 800 nm—SPP wavelength). The possibility of spatial scanning the focusing spot of SPP on the surface of Ag film is shown. [ABSTRACT FROM AUTHOR]

The authors consider possibility of interferometer construction based on plasmon-polariton structures. The strict solution results of electrodynamic excitation problem of a metal-dielectric structure have been used by outside field source as a mathematical model of the plasmon-polariton structure. This paper describes work principle of plasma corrugated-rod structure of length 4λ with a complex surface impedance profile and as a result interference field distribution has been calculated. Resulting interference field distribution has been obtained by numerical modelling and during the experiment. [ABSTRACT FROM AUTHOR]

Nonlinear plasmonic effects in perspective 2D materials containing low-dimensional quantum emitters can be a basis of a novel technological platform for the fabrication of fast all-plasmonic triggers, transistors, and sensors. This article considers the conditions for achieving a strong coupling between the surface plasmon−polariton (SPP) and quantum emitter taking into account the modification of local density of optical states in graphene waveguide. In the condition of strong coupling, nonlinear interaction between two SPP modes propagating along the graphene waveguide integrated with a stub nanoresonator loaded with core−shell semiconductor nanowires (NWs) was investigated. Using the 2D full-wave electromagnetic simulation, we studied the different transmittance regimes of the stub with NW for both the strong pump SPP and weak signal SPP tuned to interband and intraband transition in NW, respectively. We solved the practical problem of parameters optimization of graphene waveguide and semiconductor nanostructures and found such a regime of NW−SPP interaction that corresponds to the destructive interference with the signal SPP transmittance through the stub less than 7 % in the case for pump SPP to be turned off. In contrast, the turning on the pump SPP leads to a transition to constructive interference in the stub and enhancement of signal SPP transmittance to 93 % . In our model, the effect of plasmonic switching occurs with a rate of 50 GHz at wavelength 8 µ m for signal SPP localized inside 20 nm graphene stub loaded with core−shell InAs/ZnS NW.

We examine the momentum and angular momentum (AM) properties of monochromatic optical fields in dispersive and inhomogeneous isotropic media, using the Abraham- and Minkowski-type approaches, as well as the kinetic (Poynting-like) and canonical (with separate spin and orbital degrees of freedom) pictures. While the kinetic Abraham–Poynting momentum describes the energy flux and the group velocity of the wave, the Minkowski-type quantities, with proper dispersion corrections, describe the actual momentum andAMcarried by the wave. The kinetic Minkowski-type momentum and AMdensities agree with phenomenological results derived by Philbin. Using the canonical spin– orbital decomposition, previously used for free-space fields, we find the corresponding canonical momentum, spin and orbitalAMof light in a dispersive inhomogeneous medium. These acquire a very natural form analogous to the Brillouin energy density and are valid for arbitrary structured fields. The general theory is applied to a non-trivial example of a surface plasmon-polariton (SPP) wave at a metal-vacuum interface.Weshow that the integral momentum of the SPP per particle corresponds to the SPP wave vector, and hence exceeds the momentum of a photon in the vacuum.Wealso provide the first accurate calculation of the transverse spin and orbital AM of the SPP. While the intrinsic orbital AM vanishes, the transverse spin can change its sign depending on the SPP frequency. Importantly, we present both macroscopic and microscopic calculations, thereby proving the validity of the general phenomenological results. The microscopic theory also predicts a transverse magnetization in the metal (i.e. a magnetic moment for the SPP) as well as the corresponding direct magnetization current, which provides the difference between the Abraham and Minkowski momenta. [ABSTRACT FROM AUTHOR]

Thermal radiation emitted from flat facet edges of an aluminum bar has been experimentally investigated. It is established that the radiation is predominantly p -polarized and has the pattern with a pronounced maximum oriented at an angle of a few degrees to the plane of the facet. In addition, the magnitude of this maximum increases with the facet length size and tends to saturation as the length increases. The facts suggest that this phenomenon occurs due to diffraction of infrared surface plasmon-polaritons (SPPs) generated by phonons of the sample. This assumption is supported by a cubic dependence of the radiation intensity on temperature, which is typical for thermally generated SPPs (TSPPs). The analytical model for computing the spectrum and the integral intensity of the entire set of TSPPs arriving to the edge of their sources line has been developed as well. [ABSTRACT FROM AUTHOR]

A new approach to the formation of a 1D planar periodicity on the front of a plasmonic photodetector based on Schottky barrier is proposed. It allows forming a 1D planar periodicity with corrugation at the 'metal/environment' interface by laser interference lithography using embedded chalcogenide wires, whereas the 'metal/semiconductor' interface is flat that leads to reducing of surface recombination losses at Shottky barrier in contrary to the conventional technology for forming corrugated metal films on the semiconductor surface requiring chemical etching of the semiconductor substrate. In this case, the metal film interfaces are quasi-anticorrelated as opposed to correlated ones in the conventional technology. It has been theoretically predicted that the polarization sensitivity ( T / T ) strongly depends on the cross-sectional shape of chalcogenide wires and reaches a value of 8. Furthermore, it was theoretically found that the maximum sensitivity of the signal intensity on the environment refractive index is three times larger than for an equivalent structure obtained by conventional technology. Comparison of experimental data for the photocurrent in the case of two types of correlation between metal film interfaces demonstrates good agreement with numerical simulations. [ABSTRACT FROM AUTHOR]

The modulation instability development of intensive surface plasmon-polariton waves in a thin metal film is studied. It is shown both analytically and numerically that the modulation-instability effect can give rise to spatial redistribution and longitudinal localization of surface plasmon-polariton wave energy on the subwavelength scale. Analytical expressions for the driving parameters of the modulation instability process − nonlinearity and dispersion − are derived. The impact of the film thickness and dielectric permittivities of constituents on the dynamics of surface plasmon-polariton wave transformation is considered. Numerical simulations show that in the layer structure comprising a silver film of subwavelength thickness a train of subpicosecond optical pulses with high repetition rate can be generated. [ABSTRACT FROM AUTHOR]

Dispersion properties and field distributions of TM (or p -polarized) surface plasmon-polaritons have been investigated in the system that a strained graphene sheet cladded by two dielectrics. The outcomes show that graphene TM surface plasmon-polaritons are bound confined modes, and the field components penetrate into the dielectric layers in the rang that is very smaller than the wavelength in the free space. At low photon energies, when the tension is along the zigzag (armchair) direction and parallel (perpendicular) to the tangential electric field, the wavelength, propagation length and penetration depth of TM surface plasmon-polaritons increase (decrease) with increasing the strain. Changing the angle between the tension direction and tangential electric field at cases with the constant strain, cause to existence of TM surface plasmon-polaritons in the wider range of frequency. [ABSTRACT FROM AUTHOR]

Here, we report the design and numeric-theoretical study of a power divider working at two different regimes in THz range based on graphene. The device is composed by a graphene disk resonator and eight graphene waveguides linked to the resonator. This graphene set is placed on a dielectric substrates stacking. Under a bias voltage applying between the graphene set and the dielectric substrate set, the divider works into biasing voltage (B.V.) regime by splitting the signal input power and increasing the ports number of transmission (from three to five output ports). Otherwise, when the resonator is undergone a DC magnetic field, the device works in magneto-plasmon (M.P.) regime by splitting the input power in similar manner as B.V. regime, but the transmission and isolation ports are different, which leads to the source protection. The working principle of B.V. and M.P. regimes are based on dipole and quadrupole resonances configurations as a function of applied external electric and magnetic fields, respectively. These two modes are excited by surface plasmon-polariton waves propagating in the graphene waveguides. Both regimes work as selector switches and provide fine results in transmission, isolation and reflection. • Regarding to communication research field, the telecommunications area has been exponentially growing, this in part thanks to the strategic area of silicon photonic integrated circuits manufacturing which has two fundamental sub-areas. The first one, being dedicated materials for nano-manufacture, in which studies are developed on new materials that show unique physical properties, such as graphene. The second area is linked with nanoeletronics devices, which covers the development of optimal designs to keep as target the excellent electrical and magnetic properties of manufactured components, as sensors, actuators, switches, chip-integrated photonic circuits, among others devices. • In this work, a new power divider working by means of two different mechanisms, designated B.V. and M.P. cases, with eight ports based on graphene and operating in the THz region is proposed and analyzed. The device composed of graphene and dielectric substrate has a very simple structure. It was optimized by adjusting physical and geometrical parameters to enlarge bandwidth and to diminish insertion loss. It is shown in the B.V. case, that the applying of an external electric field due to a bias voltage, it turns the device into a selector switch (ON/OFF state) increasing (decreasing) the transmission ports at a chosen operating frequency. For M.P. case, we have a similar behavior as B.V. case, where the transmission ports number is higher. In addition, the non-reciprocal feature of device, i.e., when it is undergone a external magnetic field at resonator, that allows the harmful reflections from output ports to be avoided. [ABSTRACT FROM AUTHOR]

Angular responses of optical transmission enhanced by surface plasmon-polaritons (SPPs) in a metal layer are investigated. Propagating SPPs on a continuous metal layer with nanostructures depend on in-plane momentum; thus, transmission peaks associated with those SPPs are inherently affected by the incident angle. Here, we report that SPP-enhanced transmission peaks can become less dependent on the incident angle by introduction of deep nanoindentations, based on numerical simulations and experiments. Field localization at indentation patterns allows propagating-coupled SPPs to have properties of localized SPPs, which appears as a form of flattened SPP energy band. Spectral transmission in a fabricated silver layer with deep nanoindentations shows comparatively fixed peak positions when the incident angle increases. [ABSTRACT FROM PUBLISHER]

The optical properties displayed by materials nanostructured with metallic inclusions are mainly driven by the excitation of surface plasmon-polaritons. With this in mind, a valid homogenization procedure must be able to describe appropriately the relationship between the geometry of the inclusions and the nature of local field modes. In this paper, we derive a corrected version of the Maxwell-Garnett model for the homogenization of nonmagnetic materials structured with cylindrical nanorod inclusions. The analytical formulation combines the Meier-Wokaun approach with the Green's function method for source regions to rigorously depict the impact of shape and size of the inclusions on the effective permittivity of those media. From the comparison to the respective results obtained by the Maxwell-Garnett formalism corrected for spheres and prolate spheroids, we show that our deduction provides further reliability in describing the spectral variation of the effective permittivity, particularly at the resonance regions. Moreover, we perform a comparison to the results given by the Bruggeman model in order to evidence that the nature of local field modes is also crucial in regarding the Maxwell-Garnett approach as a suitable choice to retrieve the effective resonance characteristics. [ABSTRACT FROM AUTHOR]

The main problems preventing wide spreading of solar cells as alternative energy sources are their high cost and low efficiency. Efficiency of solar cells based on semiconductor materials is limited due to high electrical and optical losses and due to recombination processes. Non-continuous, thin island gold films deposited on a dielectric or semiconductor surface introduce a unique behavior. In response to light exposure in certain range, the metal islands present a resonant absorption of light accompanied with a collective behavior of free electrons in these islands. In this paper we present one possible way to increase the efficiency of solar cells by using nano-dimensional gold islands imbedded in semiconductor junctions. [ABSTRACT FROM AUTHOR]

Abstract: A coupled system of semi-infinite one-dimensional photonic crystal coated with metal and magnetic films is proposed. The properties of hybrid states of surface plasmon–polaritons, magnetic defect mode and optical Tamm state from the system have been studied through the Bloch theorem of periodic structure and the transfer matrix method. In the hybrid states the magneto-optical effect is amplified due to the field resonance amplification at the interface between the metal and magneto-optical material. Tunable nonreciprocal propagation can be achieved from the hybrid states through changing the thickness of magneto-optical material layer. The nonreciprocity is found to be robust to the change of metal thickness. [Copyright &y& Elsevier]

The enhancement factor for surface plasmon-polaritons scattering by a thin dielectric grating was measured experimentally. Scattering of a p-polarized wave may be up to 30,000 times stronger than the non-resonant scattering of an s-polarized wave by the same grating. A detailed comparison between the theoretical calculations and experimental measurements was performed. Strong localization of the scattered field near the edges of diffraction grating grooves was found. Such localization is very promising for numerous applications, e.g., biological sensors, optical tweezers for catching particles, or viruses, etc. [ABSTRACT FROM AUTHOR]

This Letter reports on the assembly on the tip of an optical fibre of a metamaterial film fabricated by a self-assembly bottom-up method, composed of silver nanowires embedded in an alumina matrix. By illuminating the film through the fibre in a reflection configuration, we observe experimentally the optical response of the metamaterial in agreement with theoretical predictions and interpreted as the excitation of surface plasmon-polaritons in the cylindrical surface of the nanowires. These results pave the way for low-cost optical fibre devices that incorporate metamaterial films. [ABSTRACT FROM AUTHOR]

We discuss the properties of surface plasmons-polaritons in graphene and describe four possible ways of coupling electromagnetic radiation in the terahertz (THz) spectral range to this type of surface waves: (i) the attenuated total reflection (ATR) method using a prism in the Otto configuration, (ii) graphene micro-ribbon arrays or monolayers with modulated conductivity, (iii) a metal stripe on top of the graphene layer, and (iv) graphene-based gratings. The text provides a number of original results along with their detailed derivation and discussion. [ABSTRACT FROM AUTHOR]

Lead forms elongated islands when grown on vicinal Si(111) surfaces. Polarized infrared transmittance studies have shown a strong anisotropic optical response associated with antenna-like plasmonic resonances, whose spectral position in the region of 0.25 eV is sensitive to the length of the islands. Reflection anisotropy spectroscopy (RAS) using a photoelastic modulator (PEM) should be more sensitive to such optical anisotropies, but becomes difficult below ∼0.5 eV for instrumental reasons. Measurements of the anisotropic response, in reflectance, of Pb islands grown on Si(557)-5 × 1-Au are extended down to ∼0.12 eV by combining sample rotation with tuneable femtosecond laser irradiation from a difference frequency generator. The extended RAS spectral range allows the full anisotropic nanoparticle plasmon-polarition optical response in the surface plane to be explored for this type of material system. Reasonable agreement with a simple nanoantenna model of the resonance maximum is obtained, but calculating the full line profile of the RAS response of supported nanoparticles remains challenging. [ABSTRACT FROM AUTHOR]

We present calculations of the efficiency of excitation of surface plasmon-polaritons (SPPs) with surface structures illuminated by focussed beams. First, it is shown that the low reflectivity observed with broad highly directional beams and periodic gratings does not necessarily imply an efficient coupling to SPPs. We then consider the coupling through surface features like steps, grooves and angled steps, and calculate efficiency maps for these structures as functions of the parameters that define them. Finally, we explore the possibilities of improving the coupling efficiency using periodic structures consisting of a small number of rectangular grooves. We find that a surface section with a length of about four wavelengths can couple as much as 45% of the incident light into a directional SPP. [ABSTRACT FROM AUTHOR]

Abstract: The method for calculation of the local field factor that describes electrodynamical properties of three-layered systems with 2D photonic crystal is proposed. Analytical calculations are performed in the frame of Green function method on the base of the effective susceptibility concept. The possibility of surface waves amplification by direct electrical current in the systems under consideration is studied. Numerical analysis clearly proves the presence of convective instability. It means that three-layered systems can be considered as a surface waves’ amplifier. Because of periodical structure the phase synchronism domain lies in the range of entirely accessible in practice values of wave vector and frequency. The experimental setup and real systems parameters for observation of surface waves amplification effect are discussed. [Copyright &y& Elsevier]