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We numerically investigate the optical forces in stereometamaterials composed of two-dimensional arrays of two spatially stacked split ring resonators with a twisted angle. At the hybridized magnetic resonances, we obtain both attractive and repulsive relative optical forces, which can be further exploited to control the separation between the two split ring resonators. Due to the strongest inductive coupling achieved for a twist angle of 180°, an attractive relative force as high as ~1200 piconewtons is realized at illumination intensities of 50 mW/µm(2). We show that a quasi-static dipole-dipole interaction model could predict well the characteristic and magnitude of the relative optical forces. We also demonstrate that although the optical force exerted on each of the split ring resonators could be oriented in a direction opposite to the propagation wave vector, the mass center of the two resonators is always pushed away from the light source.

High performance light absorber with a broad bandwidth is particularly desirable for near-infrared photodetection and optical interconnects. Here we demonstrate a dual broadband perfect absorber in the near-infrared regime, which is based on a hybrid plasmonic-photonic microstructure. Such a microstructure is fabricated by self-assembling a monolayer colloidal crystal on an optically opaque metal film followed by depositing a thin metallic half-shell on the top of the colloidal particles. Both experimental and numerical simulation results show that the simply designed absorbers have dual broadband with absorption exceeding 90% in the near-infrared region with the absorption bands being scalable by tuning the size of the colloidal particles. Moreover, the absorption efficiency shows an extremely slight dispersion for the incident angles up to 50 degrees, benefit from the high symmetry as well as the highly modulated plasmonic microstructures that lead to a weak polarization dependence of these two absorption bands. The relative ease of growing high-quality colloidal crystals and the low cost of fabricating such plasmonic-photonic microstructures with high reproducibility could promise applicability of the light absorber in the field of photodetectors, thermal emitters and photovoltaics.

The near infrared transmission of corrugated metal films deposited on hetero-colloidal crystals is investigated. The transmission response of the quasi-three-dimensional (quasi-3D) metal film is modified by controlling the nominal thickness of a dielectric layer pre-deposited on the top surface of the colloidal crystal to form a new hetero-colloidal crystal. An extraordinary optical transmission (EOT) phenomenon could be presented in such metallodielectric (MD) architectures. We have found that the main transmission peak is suppressed as the thickness of the intercalated dielectric layer is increased. We propose that the observed EOT is a result of constructive interference between a localized sphere-like plasmon mode and an index-guided eigen mode mainly confined in the colloidal crystal, which is confirmed by our numerical simulations. Based on the MD microstructures, a distinct plasmon sensitivity response difference is achieved, which indicates potential applications for biochemical sensing.

We numerically study the effect of the symmetry breaking on surface plasmon (SP) modes in two-dimensional dense arrays of truncated metal nanoshells (nanocups), by investigating light transmission through the arrays. We show that localized spherelike and voidlike Mie SP modes, and delocalized Bragg-type SP modes in complete nanoshell arrays become progressively weak and finally disappear when the opening angle of nanocups is increased to tens of degrees. Under higher degree of symmetry breaking, however, the coupling between spherelike and voidlike SP modes leads to an enhancement of SP resonances even though these modes are weakly excited, due to the large optical cross section of voidlike modes. Energy variations of the hybridized mode versus the opening angle are well predicted using a plasmon standing wave model. Furthermore, disappeared Bragg-type SP modes could be re as a result of near-field coupling via hot spots around the rims of nanocups., (© 2011 Optical Society of America)

In this paper, we introduce an entirely new solar absorber design—a multi-layer periodic stacked structure. Through coupling effects, this design has perfect ultra-wideband absorption characteristics. The absorber structure is composed of four absorption units with varying cycle lengths, which are cyclically stacked on the surface of the refractory metal Cr. Each cycle encompasses three-layer nanosheets of Ti–SiO2–GaAs. We verify through finite difference time domain method (FDTD) simulations that the absorber achieves an absorption efficiency of 97.8% within the wavelength range of 280 nm to 3000 nm, with an average efficiency of 96.6% under the AM1.5 standard solar spectrum. The absorber can achieve such a remarkable absorption effect because of surface plasmon resonance (SPR) and Fabry–Pérot resonance effects. At 1500 K, this structure exhibits a thermal radiation efficiency of up to 97.83%. Furthermore, the design is not affected by polarization and it is less affected by the incident angle of the light source. These absorption spectra remain consistent regardless of whether it is in the TE or TM mode. Even when the angle of incidence is increased to 60 degrees, the absorption efficiency remains high. Its unique structure and excellent performance characteristics provide higher solar energy efficiency. These outstanding features enable solar absorbers to have broad application potential in improving solar energy efficiency. [ABSTRACT FROM AUTHOR]

This paper presents a photonic crystal fiber (PCF) sensor that can be used to measure the temperature and magnetic field simultaneously, and to monitor the changes in them in the environment. When we designed the fiber structure, two circular channels of the same size were added to the fiber to facilitate the subsequent addition of materials. A gold film is added to the upper channel (ch1), and the channel is filled with a magnetic fluid (MF). The sensor can reflect changes in the temperature and magnetic field strength. The two channels containing MF and PDMS in the proposed fiber are called ch1 and ch2. The structure, mode and properties (temperature and magnetic field) were analyzed and discussed using the finite element method. By using the control variable method, the influence of Ta2O5 or no Ta2O5, the Ta2O5 thickness, the diameter of the special air hole, the distance from the fiber core and the distance between them in the displacement of the loss spectrum and the phase-matching condition of the coupling mode were studied. The resulting maximum temperature sensitivity is 6.3 nm/°C (SPR peak 5), and the maximum magnetic field sensitivity is 40 nm/Oe (SPR peak 4). Because the sensor can respond to temperature and magnetic field changes in the environment, it can play an important role in special environmental monitoring, industrial production and other fields. [ABSTRACT FROM AUTHOR]

We designed a metamaterial far-infrared absorber based on an MDM (metal–dielectric–metal) structure. We made a hollow crossed Ti microstructure at the top of the absorber. It is known that the coupling effect of equipartitional exciton resonance and intrinsic absorption at the surface of the depleting material has a strong influence on the absorber. Based on this, we investigated the absorption characteristics of the absorber using the Finite Difference in Time Domain (FDTD) theory. The results show that the absorber absorbed more than 90% of the light within a bandwidth of 12.01 μm. The absorber has an average absorption of 94.08% in the longwave infrared (LWIR) to ultra-longwave infrared (UWIR) bands (10.90–22.91 μm). The polarization insensitivity of the designed absorber is demonstrated by analyzing the absorption spectra of the absorber at different polarization angles. By adjusting the relevant geometric parameters, the absorption spectrum can be independently adjusted. Furthermore, the absorber exhibits good incidence angle insensitivity in both transverse electric (TE) and transverse magnetic (TM) modes. The absorbers are simple and easy to configure for applications such as optical cloaking, infrared heat emitters, and photodetectors. These advantages will greatly benefit the application of absorbers in practice. [ABSTRACT FROM AUTHOR]

This paper presents a new theoretical proposal for a surface plasmon resonance (SPR) terahertz metamaterial absorber with five narrow absorption peaks. The overall structure comprises a sandwich stack consisting of a gold bottom layer, a silica medium, and a single-layer patterned graphene array on top. COMSOL simulation represents that the five absorption peaks under TE polarization are at fI = 1.99 THz (95.82%), fⅡ = 6.00 THz (98.47%), fⅢ = 7.37 THz (98.72%), fⅣ = 8.47 THz (99.87%), and fV = 9.38 THz (97.20%), respectively, which is almost consistent with the absorption performance under TM polarization. In contrast to noble metal absorbers, its absorption rates and resonance frequencies can be dynamically regulated by controlling the Fermi level and relaxation time of graphene. In addition, the device can maintain high absorptivity at 0~50° in TE polarization and 0~40° in TM polarization. The maximum refractive index sensitivity can reach SV = 1.75 THz/RIU, and the maximum figure of merit (FOM) can reach FOMV = 12.774 RIU−1. In conclusion, our design has the properties of dynamic tunability, polarization independence, wide-incident-angle absorption, and fine refractive index sensitivity. We believe that the device has potential applications in photodetectors, active optoelectronic devices, sensors, and other related fields. [ABSTRACT FROM AUTHOR]

Here, we document a D-type double open-loop channel floor plasmon resonance (SPR) photonic crystal fiber (PCF) for temperature sensing. The grooves are designed on the polished surfaces of the pinnacle and backside of the PCF and covered with a gold (Au) film, and stomata are distributed around the PCF core in a progressive, periodic arrangement. Two air holes between the Au membrane and the PCF core are designed to shape a leakage window, which no longer solely averts the outward diffusion of Y-polarized (Y-POL) core mode energy, but also sets off its coupling with the Au movie from the leakage window. This SPR-PCF sensor uses the temperature-sensitive property of Polydimethylsiloxane (PDMS) to reap the motive of temperature sensing. Our lookup effects point out that these SPR-PCF sensors have a temperature sensitivity of up to 3757 pm/°C when the temperature varies from 5 °C to 45 °C. In addition, the maximum refractive index sensitivity (RIS) of the SPR-PCF sensor is as excessive as 4847 nm/RIU. These proposed SPR-PCF temperature sensors have an easy nanostructure and proper sensing performance, which now not solely improve the overall sensing performance of small-diameter fiber optic temperature sensors, but also have vast application prospects in geo-logical exploration, biological monitoring, and meteorological prediction due to their remarkable RIS and exclusive nanostructure. [ABSTRACT FROM AUTHOR]

Recently, graphene plasmons with an excellent tenability by doping or gating have been drawing increasing interest. In this work, we designed graphene-based superlens to achieve subwavelength optical imaging. We systematically investigated the imaging property in monolayer and multi-layer graphene structures and discussed in detail the effects of possible physical quantities. We found that the image resolution of the graphene-based superlens could be better than λ/50, since graphene plasmons could significantly amplify evanescent waves carrying the high spatial frequency information of the object, and restore them at the image plane. [ABSTRACT FROM AUTHOR]

We present a straightforward method to realize Fanolike resonance due to diffraction coupling of localized surface plasmon (SP) resonances by embedding the nanoantenna arrays into the substrate. Light transmission spectra of the embedded nanoantenna arrays are theoretically studied and show a Fanolike resonance resulting from the interference between localized SP resonances excited on individual plasmonic nanoantennas and an in-plane propagating collective surface mode arising from the array periodicity. The effect can be attributed to the fact that our approach, by embedding the nanoantenna arrays into the substrate, offers a more homogeneous dielectric background allowing stronger diffraction coupling among nanoantennas leading to the Fanolike resonance. Upon the excitation of this Fanolike resonance, a nearly 110 times enhancement of electric fields was achieved as compared with the purely resonance. More importantly, we also found that in addition to the above requirement of homogeneous dielectric background, only a collective surface mode with its electric field parallel to the array plane can mediate the excitation of such a Fanolike resonance. The steep dispersion of the Fano resonance profile and enhanced electric fields obtained in these structures could be attractive for biosensing and nonlinear photonics applications. [ABSTRACT FROM AUTHOR]

Recent research effort towards developing novel metal nanoparticles (NPs) and their ordered arrays have been motivated by the emergence of plasmonics. In particular, tuning the size, morphology, composition and the separation of metal NPs has allowed us to engineer the collective properties of plasmonic crystals for specific applications. Here we present our recent development of bottom-up growth methods and demonstrate convenience for the preparation of such plasmonic materials. By implementation of physical, chemical, or electrochemical deposition of a metal in combination with micromolding on two-dimensional colloidal crystals, metallic NPs with a variety of morphologies can be created in an ordered lattice. The prepared novel plasmonic crystals could find applications in optics, optoelectronics, materials science, sensing and biophysics. [ABSTRACT FROM AUTHOR]

In this study, we investigate a physical mechanism to improve the light absorption efficiency of graphene monolayer from the universal value of 2.3% to about 30% in the visible and near-infrared wavelength range. The physical mechanism is based on the diffraction coupling of surface plasmon polariton resonances in the periodic array of metal nanoparticles. Through the physical mechanism, the electric fields on the surface of graphene monolayer are considerably enhanced. Therefore, the light absorption efficiency of graphene monolayer is greatly improved. To further confirm the physical mechanism, we use an interaction model of double oscillators to explain the positions of the absorption peaks for different array periods. Furthermore, we discuss in detail the emerging conditions of the diffraction coupling of surface plasmon polariton resonances. The results will be beneficial for the design of graphene-based photoelectric devices. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel tunable THZ absorber consisting of a patterned graphene layer and a metal plate separated by a vanadium dioxide dielectric layer. The absorbent has a simple structure, is easy to make graphene patterns, and has a dual regulatory function. The ability to double regulate comes from the fact that the state of vanadium dioxide changes with the temperature between the insulating phase and the metal phase, resulting in a change in its conductivity. When vanadium dioxide is in the insulating phase, the total reflection characteristics of the absorber are >7 THz, and when vanadium dioxide is in the metallic phase, the absorber achieves near-perfect absorption in the ultra-wideband range of 3 THz to 12.4 THz (9.4 THz). Local surface plasmon resonance explains the perfect absorption. Compared with previous absorbers, our proposed absorbers are not only simple in structure, the graphene pattern is also easy to process, but also have double adjustment and perfect absorption in the ultra-wideband range, are not sensitive to polarized light, and have large tolerances for the Angle of incident. The further development and enrichment of terahertz metamaterials and metasurface devices will also have beneficial implications for terahertz wave applications in sensing, communications, and radar. Due to their significant application value in stealth, detection, and communication, metamaterial absorbers have become a research hotspot in the field of metamaterials. [Display omitted] • The absorber can realize ultra-wideband absorption from terahertz band to near infrared band. • This device achieves dual control by changing temperature and Fermi level. [ABSTRACT FROM AUTHOR]

We present and study a bidirectional metamaterial-perfect absorber based on TiO 2 -InAs regular hexagonal pattern thin films and gold grating. We employ the finite difference time domain approach for simulation. Multi-narrowband perfect absorption and ultra-wideband perfect absorption can alternate as the light source's direction changes. Four narrow-band absorption peaks developed at 987 nm, 1188 nm, 1510 nm, and 2091 nm, respectively, when the incident light struck the bottom. The corresponding absorption efficiencies were 99.69 %, 99.41 %, 98.54 %, and 98.97 %. The broadband region displays the properties of perfect absorption when incident light strikes the top. It should be noted that it is not affected by the polarization or angle of the incidence. With an average absorption efficiency of 96.02 %, the structure attains over 90 % absorption in the 3023 nm range (424–3447 nm). Second, the weighted absorption efficiency of the full spectrum is as high as 96.84 %, and the AM 1.5 solar radiation spectrum and the solar absorption spectrum are strongly coincident. Furthermore, the computation results show that the thermal radiation efficiency is greater than 95 % between 300 K and 1500 K. The electric field distribution revealed that the Fabry-Perot cavity resonance within the film, the surface plasmon resonance (SPR) on the surface of the InAs and TiO 2 regular hexagonal pattern films, the interstitial mode excitation between the films, and the excitation cavity coupling between cells of each unit were primarily responsible for the perfect absorption of broadband. The high-order resonant coupling in the FP cavity and the strong coupling between the local surface plasmon resonance and the FP cavity resonance in the metal grating's slit are the primary causes of the narrow band's perfect absorption. The suggested bidirectional metamaterial perfect absorber has significant promise for use in the disciplines of sensing, solar energy absorption, photoelectric detection, and photothermal conversion, as evidenced by its superb absorption and thermal radiation characteristics. Based on Au grating and TiO 2 -InAs regular hexagonal pattern sheets, a perfect metamaterial absorber capable of bidirectional switching between narrowband and broadband absorption is presented. When a light source illuminates the bottom of a bidirectional metamaterial perfect absorber (BDMPA), multi-narrow band perfect absorption occurs. Four resonant absorption peaks were seen at 987 nm, 1188 nm, 1510 nm, and 2091 nm, with absorption efficiencies of 99.69 %, 99.41 %, 98.54 %, and 98.97 %, respectively. When the light source illuminates the top of this BDMPA, it achieves perfect ultra-wideband absorption. The absorption rate exceeds 90 % between 424 and 3447 nm, the bandwidth reaches 3023 nm, and the average absorption efficiency is 96.02 %. [Display omitted] • > When incident light hits the bottom, four resonant peaks with absorption greater than 98 % are achieved. • > When incident light hits the top, the absorber achieves an absorption bandwidth of 3023 nm for efficiencies above 90 %, and 2283 nm for efficiencies above 95 %. • > The thermal radiation absorption efficiency is greater than 95 % in the range of 300–1500 K. [ABSTRACT FROM AUTHOR]

• The CST and theoretical calculations show that the absorber has a working band of 38.64–227.76 THz, completely covering the THz band and has a relatively uniform absorption peak distribution, indicating that the absorber has a high applied value. • The absorber has four perfect absorption bands, 43.44–50.4 THz,62.48–72.96 THz,85.68–87.12 THz and 192.24–195.36 THz, indicating that the absorber is wavelength selective. • The absorber can adjust the absorption characteristics by changing the Fermi energy of the graphene. • The absorber has high refractive index sensitivity and good sensing performance. This paper proposes an ultra-broadband absorber operating in the terahertz band, utilizing the surface plasmon resonance characteristics of micron-scale structured Dirac semimetals and single-layer graphene and the bound-state electromagnetic coupling effect in the continuum domain. The performance of the absorber was verified by finite difference method simulation. Its average absorption rate reached 92 % in the range of 38.64–227.76 THz. Where 43.44–50.4 THz, 62.48–72.96 THz, 85.68–87.12 THz and 192.24–195.36 THz band with an average absorption rate of 99 %. The study also explored the Fermi level and relaxation time of graphene and found that the absorber has good physical tunability. The absorber has a structural symmetry, independent of the polarization. Compared with previous designs, the absorber designed in this paper has a simple structure, is easy to adjust, is insensitive to large angles, and has extensive application potential in solar energy, photoelectric detection, sensors and other fields. [ABSTRACT FROM AUTHOR]

• The FDTD simulation reveals the phenomenon that the absorber has a large bandwidth with high absorptivity and two resonance absorption peaks in the mid-long infrared band, which indicates that the absorber has absorption selectivity. • By changing the geometric structure parameters of the absorber, the absorptivity of the absorber in the middle and long infrared band is adjusted. • The polarization insensitivity and Angle independence of the absorber are determined by simulating the absorption characteristic curves of the absorber at different incident angles and polarization modes. • By adding different kinds of metals and media types, comprehensive selection of better performance combination, to meet our needs. Infrared band occupies a very important position in the electromagnetic wave band. Traditional infrared devices use the inherent properties of natural materials to achieve the regulation of electromagnetic waves, but the limited ability of such devices to regulate electromagnetic waves can't well meet our needs. In this paper, we reported a metamaterial absorber of Cr-Si 3 N 4 -Cr-Si 3 N 4 -Ti based on double-layer metal-insulator-metal (MIM). It is investigated with the optimal structural parameters of 490 nm, 330 nm, 30 nm, 720 nm, 120 nm, in descending order, at which the absorptive properties are studied. When the light wave is incident vertically, it can be obtained from the experimental simulation that this absorber has polarisation insensitivity. Because of the coupling effect of the surface plasmon resonance and the high-loss material, the bandwidth of absorption greater than 90% can reach 9190 nm, and the average absorption in the target long-wave infrared band (9.506∼18.145 μm) is 94.8%. By selecting different geometrical parameters of the structure, the absorption spectrum can be adjusted independently. In addition, the absorber has good incident angle insensitivity in TE and TM modes. Also, the absorber we proposed has a plain structure, is convenient for manufacturing, the material is easier to obtain, which ensures a good absorption bandwidth and average absorptivity, and the study of this metamaterial absorber has important applications in solar cells, satellite radiothermographs, photodetectors, and spectral imaging. In this work, we simulate and calculate the performance of a broadband absorber based on a double-layer MIM structure. The results show that the absorber can achieve an average absorption of 90% in the range of 9.48–18.67 μm and 94.8% in the targeted longwave infrared band (9.506–18.145 μm). In response to the broadband absorption, we designed the schematic structure of the absorber based on the MIM (metal-dielectric-metal) structure. The structure of each cell is composed of a two-layer MIM structure, from top to bottom, Cr, Si 3 N 4 ,Cr,Si 3 N 4 ,Ti.The simulation results show that two resonant modes are generated at 10.25μm and 16.75μm, and the absorption rates are 98.9% and 99.3%, respectively. Then, the geometric parameters of the structure are adjusted respectively to get the best parameter values. In addition, the comparison of several different microstructures proves the advantages of our designed structure. We also simulate the absorption characteristic curves at different incidence angles and different polarization modes. Finally, we compare by changing the type of metal and medium. To sum up, the absorbers designed by us have the characteristics of broadband high absorptivity, no relation between polarization and incidence Angle, and simple structure. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a plasmonic refractive index (RI) sensor based on a composite structure comprising a gold nano-cross array on a gold nanofilm and a SiO 2 spacer is proposed. Surface plasmon resonance is excited by a plane wave which perpendicular to the top surface of the composite structure. A part of the incident electromagnetic wave was transferred to the propagating surface plasmon (PSP) on the upper surface of the gold thin film, while another part was coupled to the localized surface plasmon (LSP) by the gold nano-cross array. Within a certain range, the geometric parameters have less influence on the sensing performance of the composite structure. Numerical results show that the maximum RI sensitivity and figure of merit (FOM) are 872 nm/RIU and 97 RIU−1 in gas environments, and 880 nm/RIU and 98 RIU−1 in liqud environments. The proposed composite structure has broad application prospects in biological and chemical fields. [ABSTRACT FROM AUTHOR]

We propose a broad band and high absorption adjustable ideal absorber. The whole structure is Cr-Ge-Si 3 N 4 -Ti from bottom to top. The simulation results show that three resonant absorption modes are generated at 9.15 μm, 10.68 μm and 15.17 μm, with absorption rates of 92.1%, 97.3% and 95.2%, respectively. The bandwidth of the absorber is broadened by adding a lossy dielectric layer. Then, the control variables of the structural geometry parameters of the absorber were studied respectively to obtain the best optimization parameters. Since then, comparisons of different underlying microstructures have confirmed the uniqueness of our structure. Finally, we simulate the absorption of the absorber in different polarization modes with varying incident angles. In addition, the performance of previous work and our absorber are compared. These studies show that our absorber has active tunability, polarization and incident angle sensitivity, and high absorption bandwidth. [Display omitted] • The results of FDTD theory show that the absorber based on MDM structure has high absorption bandwidth and three resonant absorption peaks in the mid-infrared band, which indicates that the absorber has wavelength selectivity. • By tuning the geometric parameters of the absorber structure, the active tuning of the absorber in a wide range is realized. • The absorption of the absorber under the change of incident angle and polarization mode is simulated, and it is determined that the absorber is insensitive to polarization and incident angle. • By adding a lossy dielectric layer, the bandwidth of the absorber can be broaded. Long wavelength infrared (LWIR) wideband absorption is an important target in the research of middle infrared band. In this work, we study the absorption characteristics of Cr-Ge-Si 3 N 4 -Ti metamaterial absorber based on nanowire cross surrounding. The absorber has polarization independence when the light wave is incident vertically. Due to the coupling of surface plasmon resonance and the intrinsic absorption of lossy material, the numerical simulation calculation shows that the bandwidth with absorptivity greater than 90 % reaches 7.23 μm, and the average absorptivity in the LWIR band (8.98–16.21 μm) is 94.1 %. The absorption spectrum can be adjusted independently by changing the geometric parameters of the structure. Moreover, the absorber has excellent incident angle insensitivity in TE and TM modes. The designed absorber is simple in structure, easy to configure, and suitable for infrared imaging, thermoelectronic devices and thermal detection applications. [ABSTRACT FROM AUTHOR]

A triple-band ultra-perfect absorber with tunability based on graphene surface plasmon resonance is investigated and proposed in this article. According to the finite difference time domain (FDTD) method, in the mid-infrared wavelength range of 3400 nm ∼ 4000 nm, we have identified three perfect absorption peaks, namely at λ 1 = 3548.54 nm, λ 2 = 3660.25 nm and λ 3 = 3912.99 nm, in which the absorption rate 99.90 %, 99.05 %, 99.13 % respectively. By discussing different graphene geometries, this paper shows the best results of this experiment. If we want to control the amplitude of the absorption peak and the wavelength of the resonance, we can do so in two ways: first, by changing the Fermi energy level of the graphene, and second, by changing the relaxation time of the graphene. Besides, the absorbed resonant waves can slao be controlled by adjusting the refractive index of the environment in which they are located and the refractive index of SiO 2. The absorber exhibits polarisation and angle insensitivity, so when the angle of incidence varies in the (0° ∼ 50°) range, the absorber we have designed also maintains high absorption. Three resonance absorption peaks with sensitivities of 845.7 nm/RIU, 880.3 nm/RIU and 942.6 nm/RIU can be obtained from the results of the simulations. In summary, we believe that the absorber with its various characteristics could be of great value in a number of applications. [Display omitted] • A model structure for the absorption of light by graphene in the mid-infrared band is proposed. • By FDTD simulation, the absorber has three perfect narrow band absorption peaks. • Several factors that affect the efficiency of the absorber are discussed. • The absorption property can be turned by controlling chemical potential or relaxation time. [ABSTRACT FROM AUTHOR]

We studied theoretically light transmission through a planar rectangular array of silver circular disks. An asymmetric lineshape, which is characteristic of the Fano resonance, has been found in a narrow frequency range of the spectrum. The effect can be attributed to the strong coupling between localized particle plasmon resonances excited on individual silver circular disks and an in-plane propagating collective surface mode arising from the array periodicity, as indicated by the anticrossing behavior of the resonance positions in the transmission spectra. More importantly, it was found that a fifty-two fold enhancement of electric field was achieved as compared with the purely resonance at the excitation of this Fanolike resonance; and only a collective surface mode with its electric field parallel to the array plane can mediate the excitation of such a Fanolike resonance. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports a facile method for fabricating metallic triangular nanoparticle array with controllable interparticle distance, based on a combination of nanosphere lithography, reactive ion etching and physical sputtering technique. Light transmission spectra of the metallic triangular nanoparticle arrays with a series of interparticle distances are measured, which show a surface plasmon resonance whose position is observed to shift to longer wavelength for the polarization direction parallel to the long particle pair axis with decreasing the interparticle distance. With this structure as surface-enhanced Raman scattering substrate, the Raman signal is strongly enhanced and shows high dependence on the interparticle distance. The controllable interparticle distance and large-area ordered array of the substrate suggest its promising application in surface-enhanced Raman spectroscopy. [Copyright &y& Elsevier]