Left-handed Materials Research Articles

Negative index metamaterial at ultraviolet range for subwavelength photolithography

Abstract A negative index metamaterial (NIM) at ultraviolet range is constructed with stacked plasmonic waveguides. Based on the waveguides performing antisymmetric modes, the negative refractions of both wavevector and energy flow are realized when a TM-polarized light with a wavelength of 365 nm incidents on the plane of the layers. It is proved that the NIM could be introduced into subwavelength photolithography for extending working distance. Both theoretical and experimental results indicate that the patterns with a feature size of 160 nm can be reproduced in photoresist with a 100 nm-thick air working distance. Moreover, arbitrary two-dimensional patterns with a depth reach 160 nm can be obtained without diffraction fringe by employing a nonpolarized light. This design gives new insights into the manipulation of light. The improved working distance, well-shaped patterns over large area present an innovative method for improving subwavelength photolithography.

Hyperbolic phonon polaritons with positive and negative phase velocities in suspended α -MoO3

Sample suspension is a valuable method to improve the mechanical, thermal, electronic, and optical properties of low-dimensional materials. In terms of confined light-matter waves—the polaritons, sample suspension can elongate the wavelength of polaritons with a positive phase velocity. Previous work demonstrates a wavelength elongation of ∼10% for hyperbolic phonon polaritons (HPPs) in uniaxial crystals of hexagonal boron nitride (hBN). In this work, we report the alteration of HPPs in biaxial α-phase molybdenum trioxide (α-MoO3) by sample suspension. Our combined infrared nano-imaging experiments and electromagnetic theory reveal a wavelength elongation > 60% and a propagation length increase > 140%, due to the simultaneous wavelength elongation and dissipation elimination in the suspended specimen. We have also examined HPPs in α-MoO3 with a negative phase velocity. The sample suspension shortens the HPP wavelength and simultaneously reduces the dissipation due to the unique permittivity tensor. The HPPs with improved figures of merits in the suspended specimen may be developed for nano-polaritonic circuits, biochemical sensing, emission engineering, and energy transfer.

Design and Modelling of Double Negative Metamaterial for Microwave Sensing Application

Design and Modelling of Double Negative Metamaterial for Microwave Sensing Application

Impact of higher-order effects on modulation instability in negative index materials

In this article, we present a systematic investigation of modulation instability (MI) in negative index materials (NIMs) with higher-order dispersion and nonlinearity. We adopt the method of linear stability analysis and obtain an expression for the instability gain. Special attention is paid to studying the effect of fourth-order dispersion, quintic nonlinearity, first-order nonlinear dispersion, and second-order nonlinear dispersion on the instability gain. It is found that the fourth-order dispersion forms new instability regions and gives new ways to generate solitons or ultrashort pulse trains. Our study also shows that in the presence of higher-order dispersion a switching of the sign of cubic nonlinearity can generate two distinct MI regions. This result may provide a better way to generate different frequency ultra-short pulses as a result of switching of the sign of cubic nonlinearity by tuning the parameters of constituent elements of the metamaterials. Further, we observed that the cooperating cubic and quintic nonlinearities widen the MI by enhancing maximum gain and bandwidth, on the other hand, the competing cubic and quintic nonlinearities suppress the MI considerably.

Impact of higher order dispersions and nonlinearities on instability criterion of oppositely directed coupler in the presence of negative index material channel

This paper intends to investigate the modulational instability (MI) criterion of two core positive-negative index coupler channel setup from the obtained analytical dispersion relation for MI gain profile. The governing equation, the modified nonlinear Schrodinger equation (MNLSE) is studied for the role of higher order dispersion (HOD) and higher order nonlinearity (HON) on instability spectra of two core positive indexed coupler (PIM) and negative indexed coupler (NIM) arrangement. The HOD comprises of the second, third, fourth and fifth order linear dispersion terms and HON is inclusive of cubic, quintic, septic, cubic-quintic-septic-self-steepening (SS), and cubic-quintic-septic-intrapulse Raman scattering (IRS). Our study reveals that it is the 6th order linear dispersion term which brings in the considerable changes of MI gain spectrum in both normal and anomalous dispersion regimes. In particular, the combined effect of septic SS and IRS in two core directional coupler with NIM channel proves to be very crucial in the generation of instability gain spectra. This study has higher prospects in generation of solitary wave in two core directional system for optical fiber communication.

Research on the characteristics and equivalent circuits of left‐handed materials with the same manifestation

Two new types of heterogeneous left-handed materials (LHM) are presented in this article. By combining the split resonant ring structure with the S-shaped structure, a single-sided printed heterogeneous type I LHM is designed; By rotating and combining the designed heterogeneous type I LHM, the heterogeneous type II LHM are formed. After electromagnetic simulation and S-parameter extraction, it is confirmed that the heterogeneous type I LHM and the heterogeneous type II LHM have negative refraction characteristics at 1.8–2.3 and 2.5–3.2 GHz, respectively. After loading on the dipole antenna, the resonant frequency of the dipole antenna is reduced from 2.45 to 1.68 GHz, that is, loading heterogeneous type I and heterogeneous type II LHM can realize the miniaturization of the dipole antenna, which is 29.7% smaller than the previous design in terms of size reduction.

Optically Left-Handed Nanopearl Beads with Inductance-Capacitance Circuits at Visible-Near-Infrared Frequencies Based on Scalable Methods.

Optically left-handed materials refract the propagating light in the opposite direction. Most research has focused on the design of various structures, including split-ring resonators, either on planes or in particle cluster forms to resonate with specific light frequencies. However, for particle-based materials, the circuital structures for optical left-handedness have not been fully understood and the effect of interior structure on the optical handedness have not been investigated. Additionally, scalable methods to deploy the unique characteristics of the materials have not been reported so far and are still urgent. Here, optically left-handed nanopearl beads are synthesized in up to 1.25 L solutions. Nanopearl beads contain assembled Au nanocolloids, a dielectric sphere, and a thin silica layer that fixes the assembled structures to sustainably yield unique inductance-capacitance circuits at specific visible-near-infrared frequencies. The frequencies are tunable by modulating the interior structures. Investigation of the circuit structures and Poynting vectors generated within the nanopearl beads suggest the likelihood of their left-handedness. Moreover, the effects of interior structures on the optical handedness of the nanopearl beads are extensively investigated. The results could help commercialize optically left-handed materials and pioneer fields that have not been realized so far.

Patch Antenna Based on MUC for Wi-Fi and 5G

This communication reported the patch antenna working at Wi-Fi and 5G bands. To acquire compactness the side lengths of the patch are taken based on upper-frequency band (3.3 GHz). Dual-band operation (lower resonating band) is realized by loading the Mushroom Unit Cell (MUC) along the bottom right corner of the patch. To obtain Circular Polarization (CP) at the 5G band the conventional patch is modified with fractal boundary. This blend of the Double Negative Transmission Lines metamaterials (DNG TL), as well as fractal concepts yielded good compactness suitable for ultra-thin portable gadgets. Measured results have good correlation with simulated data from HFSS. The obtained bandwidths at the lower and upper bands are 2.51 % and 6.23 % when the Poly fractal curves are introduced. CP bandwidth of the proposed antenna at 5G band obtained from the measured data is 2.35 % which is the highest to the best of authors' knowledge for this type of thin antennas.

Simulation of electromagnetic wave propagations in negative index materials by the localized RBF-collocation method

In this paper, a fast simulation of the electromagnetic wave propagation in negative index materials is developed by the localized meshfree radial basis function (RBF) collocation method. The perfect match layer is considered on the boundary in a unit cell to avoid the wave reflection. The experienced shape parameter is validated by simple test functions. The CPU time costs are compared with those of FEM. Numerical examples of different scatterers are presented to demonstrate the efficiency of the proposed method.

Thz Flat Lenses Based on Wide-Angle, Polarization Independent 3-D Negative Refractive Index Metamaterial for Sub-Wavelength Imaging and Self-Collimation Assisted Beam Transfer Applications

Thz Flat Lenses Based on Wide-Angle, Polarization Independent 3-D Negative Refractive Index Metamaterial for Sub-Wavelength Imaging and Self-Collimation Assisted Beam Transfer Applications

Overview of Planar Antenna Loading Metamaterials for Gain Performance Enhancement: The Two Decades of Progress

Metamaterials (MTMs) are artificially engineered materials with unique electromagnetic properties not occurring in natural materials. MTMs have gained considerable attention owing to their exotic electromagnetic characteristics such as negative permittivity and permeability, thereby a negative refraction index. These extraordinary properties enable many practical applications such as super-lenses, and cloaking technology, and are used to design different electromagnetic devices like filters, polarization converters, sensors, and absorbers. Advances in MTMs have made new application fields to emerge in communication subsystems, especially in the field of antennas. MTMs are usually arranged in front or above the radiating element, or incorporated in the same substrate to improve the performance of planar antennas, in terms of improving directivity, gain, bandwidth, and efficiency, reducing the size and mutual coupling, and deflecting the radiation characteristics. High gain antennas are demanded in modern wireless communication systems. Their importance is in improving the signal strength by reducing the interference and alleviating the free space path loss. This review paper provides a brief introduction to MTMs, with the focus on their operating principles. Furthermore, a detailed study of antenna gain enhancement based on the various properties of MTMs is carried out. MTMs with low values of constitutive parameters; zero-index material (ZIM), low-index material (LIM), epsilon-near-zero (ENZ), and mu-near-zero (MNZ) are discussed in detail in the context of their capability to enhance the gain of a broad class of planar antennas. The low impedance property and lensing property, which is achieved by three different characteristics: high refractive index (HRI), gradient refractive index (GRIN), and negative refractive index (NRI) materials, are loaded to planar antennas for gain enhancement. The scope of this review has been limited to antennas that were experimentally validated in the respective source papers.

Acoustic wave propagation in permeable lossy metamaterials

This paper investigates acoustic wave propagation in gas-saturated permeable lossy metamaterials, which have different types of resonators, namely, acoustic and elastic resonators, as building-block elements. By using the two-scale asymptotic homogenization method, the macroscopic equations that govern sound propagation in such metamaterials are established. These equations show that the metamaterials can be modeled as equivalent fluids with unconventional effective density and compressibility. Analysis of these frequency-dependent and complex-valued parameters shows that the real parts of both can take negative values within frequency bands determined by inner resonances. The upscaled theory is exemplified with the case of a permeable lossy metamaterial having a unit cell comprising two unconnected fluid networks and a solid frame. One of these fluid networks is loaded with acoustic resonators (e.g., quarter-wavelength, Helmholtz resonators), while thin elastic films are present in the other one. It is shown that the propagation of acoustic waves in permeable lossy metamaterials is determined by both classical visco-thermal dissipation and local elasto-inertial resonances. The results are expected to lead to judicious designs of acoustic materials with peculiar properties including negative phase velocity and phase constant characteristic for regressive waves, very slow phase velocity, and wide sub-wavelength bandgaps.

Electrically Small Metamaterial Inspired Monopole Antenna Using Double Negative Metamaterial and Ring Resonators

This paper proposes a new metamaterial inspired electrically small multi-band monopole antenna. The proposed antenna can operate at DCS 1800 in the lower band and covers two wireless local area network (WLAN) bands in the higher band. This paper describes the design and a detailed analysis of the electrically small antenna, where the compactness is achieved by the application of double negative metamaterial on a monopole antenna and multiband operation is achieved by the addition of two ring resonators. The ground structure is modified for giving proper impedance matching at lower bands. Moreover, an additional double negative structure of similar design is also incorporated to enhance its gain. A comparative study of the proposed antenna with other reported electrically small antennas is summarized and analyzed. A prototype of the proposed antenna is fabricated on a low cost substrate and experimentally validated.

Optical Properties of Nano-circuits for Metallic and Non-Metallic Nanoparticles

Optical properties of the nanoparticles can be studied theoretically by using the lumped electronic components. The particles having >0 behaved as capacitor whereas for <0 had inductor properties on the other hand the electric field perpendicular to the components then the properties of series combinations dominates and vice versa. A first principles electronic structure based method is presented to determine the equivalent circuit representations of nanostructured physical systems at optical frequencies, via a mapping of the effective permittivity calculated for a lattice of physical nano-elements using density functional theory to that calculated for a lattice of impedances using circuit theory. Specifically, it is shown that silicon nanowires and carbon nanotubes can be represented as series combinations of inductance, capacitance and resistance. It is anticipated that the generality of this approach will allow for an alternate description of physical systems at optical frequencies, and in the realization of novel opto and nanoelectronic devices, including negative refractive index materials.

DESIGN AND SIMULATION ANALYSIS OF A TEXTILE BASED METAMATERIAL PERFECT ABSORBER FOR ENERGY HARVESTING APPLICATIONS AT WIFI BAND

Metamaterials, which are called as left-handed materials, exhibit electromagnetic properties that do not exist in nature, such as negative refractive index and reverse Doppler effect, at the frequency range for which they are designed. These unique properties of metamaterials have made them indispensable in a wide variety of applications such as sensor applications, signal absorption, antenna, and energy harvesting. In this study, the design and analysis of a metamaterial (MTM) perfect absorber at 5 GHz frequency band were performed to investigate the usability of the proposed structure in energy harvesting applications. The results of the study revealed that the proposed MTM structure has potentials to be used in energy harvesting applications.

Calculation of Dispersion Characteristics of Finlines Loaded with Anisotropic Left and Right Hand Materials

In this paper, the edge-based finite element formula for calculating the dispersion characteristics of transmission lines loaded with anisotropic left handed materials and anisotropic right handed materials with electric field as working variable is derived, and the calculation is carried out by taking unilateral finline, bilateral finline and antipodal overlapping finline as examples. Firstly, the dispersion characteristics of three modes in three kinds of finlines are compared when the relative dielectric constant and permeability are fixed; Secondly, taking the unilateral fin line as an example, the changes of dispersion characteristics with the changes of relative dielectric constant and relative permeability in each direction are calculated. The calculation method and results derived in this paper further expand the application of anisotropic left handed and right handed materials in transmission lines, and also have great guiding significance for the use of finlines in microwave devices such as mixers, filters and resonators.

Surface plasmonic Cherenkov radiation and symmetry breaking within a coherent nonlinear nanostructure

Nonlinear conversions within the plasmonic structures are important for ultrafast nanophotonics; however, the impact of higher-order dispersion on nonlinear polaritonic efficiency remains unexplored. In this work, we uncover the role of higher-order dispersion and self-steepening on nonlinear surface-plasmon polaritons (NSPPs) within a coherent plasmonic interface that comprises an atomic medium doped on top of a low-loss negative-index metamaterial (NIMM) layer. This dispersion in the atomic medium--NIMM interface yields nonlinear plasmonic phase match and resonant launching of Cherenkov SPPs. We establish time-reversal and $\mathcal{PT}$ symmetry breaking for propagated NSPPs that yield asymmetric plasmonic comb excitation and anomalous plasmonic phase singularities. Our work thereby suggests a fingerprint for nonlinear plasmonic field evolution through the appearance of a Cherenkov field and develops a framework for designing a frequency selector and nanoscopic pulse shaper, which opens prospects for nonlinear nanophotonic applications.

The transverse electric plasmonic modes in a negative refractive index black phosphorene waveguide structure

We consider the transverse electric (TE) plasmonic modes supported by black phosphorene (BP) in a parallel waveguide structure with left-handed material (LHM) instead of the conventional right-handed dielectric material. The existence condition of the TE BP surface plasmon polariton (SPP) is . When an electric field is polarized along one of the two orthogonal crystal axes, the anisotropic symmetric and anti-symmetric plasmonic modes depend on the incident optical energy, the chemical potential, and the distance between two BP sheets can be observed. The symmetric mode has a more extensive effective refractive index, which possesses stronger field confinement. With a decreasing distance d between two BP sheets, the coupling strength between the two separate BPSPP waves increases. When d is small enough, the anti-symmetric mode root does not exist. LHMs can be used to realize a TE BPSPP mode to enhance the localization of the BPSPP, which is a practical method in optoelectronic devices based on black phosphorene.

Equivalence between positive and negative refractive index materials in electrostatic cloaks

We investigate, both theoretically and numerically, the equivalence relationship between the positive and negative refraction index dielectric materials in electrostatic invisibility cloak. We have derived an analytical formula that enables fast calculate the corresponding positive dielectric constant from the negative refraction index material. The numerical results show that the negative refraction index material can be replaced by the positive refractive index materials in the static field cloak. This offers some new viewpoints for designing new sensing systems and devices in physics, colloid science, and engineering applications.

Calculation of Transmission Characteristics of Shielded Microstrip Lines Filled with Anisotropic Left-Handed and Right-Handed Materials

In this paper, the edge-based finite element formula for calculating the transmission characteristics of shielded microstrip lines filled with anisotropic materials with magnetic field as working variable is derived in detail. The filling materials include anisotropic left-handed materials and anisotropic right-handed materials, and the transmission characteristics include dominant mode cutoff wavelength and electric field structure. We mainly take Rectangular-shaped, V-shaped and Trapezoidal-shaped shielded microstrip lines as examples to calculate the transmission characteristics. The formulas and calculation examples derived in this paper have strong guiding significance for the application of anisotropic left-handed and right-handed materials in inhomogeneous transmission lines, which will further expand the use of shielded microstrip lines in optical devices such as electro-optic waveguide modulators.