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Plasmonic nanoantennas have been extensively explored to boost nonlinear optical processes due to their capabilities to confine optical fields on the nanoscale. In harmonic generation, nanoantenna array architectures are often employed to increase the number of emitters in order to efficiently enhance the harmonic emission. A small laser focus spot on the nanoantenna array maximizes the harmonic yield since it scales nonlinearly with the incident laser intensity. However, the nonlinear yield of the nanoantennas lying at the boundary of a focused beam may exhibit significant deviations in comparison to those at the center of the beam due to the Gaussian intensity distribution of the beam. This spatial beam inhomogeneity can cause power instability of the emitted harmonics when the lateral beam position is not stable which we observed in plasmon-enhanced third-harmonic generation (THG). Hence, we propose a method for deterministically designing the density of a nanoantenna array to decrease the instability of the beam position-dependent THG yield. This method is based on reducing the ratio between the number of ambiguous nanoantennas located at the beam boundary and the total number of nanoantennas within the beam diameter to increase the plasmon-enhanced THG stability, which we term as the ratio of ambiguity (ROA). We find that the coefficient of variation of the measured plasmonic THG yield enhancement decreases with the ROA. Thus, our method is beneficial for designing reliable sensors or nonlinear optical devices consisting of nanoantenna arrays for enhancing output signals.

Over the last two decades, the capabilities of metasurfaces in light modulation with subwavelength thickness have been proven, and metasurfaces are expected to miniaturize conventional optical components and add various functionalities. In this review article, various metasurface design strategies are reviewed thoroughly. First, we revisit the scalar diffraction theory to provide the basic principle of light propagation. Then, we discuss widely used design methods based on the unit-cell approach. The methods include a set of simplified steps, including the phase map retrieval and meta-atom unit-cell design. Then, we introduce recently emerging metasurfaces that may not be accurately designed using unit-cell approach. We examine unconventional metasurfaces where the conventional design methods fail and finally discuss potential design methods for such metasurfaces. This article is protected by copyright. All rights reserved.

Vectorial holography has gained a lot of attention due to the promise of versatile polarization control of structured light for enhanced optical security and multi-channel optical communication. Here, we propose a bifunctional metasurface which combines both structural color printing and vectorial holography with eight polarization channels towards advanced encryption applications. The structural colour prints are observed under white light while the polarization encoded holograms are reconstructed under laser illumination. To encode multiple holographic images for different polarization states, a pixelated metasurface is adopted. As a proof-of-concept, we devise an electrically tunable optical security platform incorporated with liquid crystals. The optical security platform is doubly encrypted: an image under white light is decrypted to provide the first key and the corresponding information is used to fully unlock the encrypted information via projected vectorial holographic images. Such an electrically tunable optical security platform may enable smart labels for security and anticounterfeiting applications., The authors present a bi-functional metasurface, combining structural color printing observed under white light and polarization encoded It is appropriate. vectorial holography. A pixelated design is used encode multiple holographic images, and they demonstrate an electrically tunable optical security platform.

There are difficulties in developing high-power and small-size terahertz (THz) sources that can be used for field applications. In an attempt to design small-size THz free-electron laser (FEL) devices capable of producing higher output powers in the THz spectral region of 1–2 THz, we have developed a microtron accelerator that can accelerate electron beams to 3–6 meV, with a macropulse current of more than 40 mA. The new THz FELs use hybrid electromagnetic (EM) undulators that are two to four times shorter in length than the previous undulator and waveguide resonators with mode cross-sectional areas that are more than two times smaller than the parallel-plate waveguide in the existing FEL. We confirm that the gains and losses of the compact FELs are sufficient for lasing, and we estimate that average output power of approximately 1 W is possible with an efficiency approximately 10 times greater than the existing FEL. The minimum size of the THz FEL system, including a high-voltage pulse modulator, is estimated to be approximately 1.5 m × 2.0 m.

Structural coloration using metasurfaces has been steadily researched to overcome the limitations of conventional color printing using pigments by improving the resolution, lowering the toxicity, and increasing the durability. Many metasurfaces have been demonstrated for dynamic structural coloration to convert images at the visible spectrum. However, the previous works cannot reach near-zero scattering when colors are turned-off, preventing it from being cryptographic applications. Herein, we propose a completely on/off switchable structural coloration with polarization-sensitive metasurfaces, enabling full-colored images to be displayed and hidden through the control of the polarization of incident light. It is confirmed that the nanostructure exhibits the polarization-dependent magnetic field distributions, and near-zero scattering is realized when the polarization of incident light is perpendicular to the long axis of the nanofins. Also, the metasurfaces are made up of triple-nanofin structures whose lengths affect locations of resonance peaks, resulting in full-color spectrum coverages. With such advantages, a QR code image, a two-color object image, and an overlapped dual-portrait image are obtained with the metasurfaces. Such demonstrations will provide potential applications in the fields of high-security information encryption, security tag, multichannel imaging, and dynamic displays.

Squeezing photons into deep sub-wavelength volumes and few-nanometer gaps has led to the investigation of interesting phenomena, including strong coupling, quantum plasmonics, nonlinearity enhancement, nonlocality, and molecular junctions. The common configuration of bowtie nanoantennas has been extensively studied owing to the great enhancement of the localized electromagnetic field. The enhancement rapidly increases as the tips become sharper and the gap becomes narrower. However, reliable fabrication of nanoantennas that are extremely sharp with sub-10 nm gaps is statistically prohibited due to the fundamental limitation of the proximity effect of electron beam lithography. Here, an intuitive “fall-to-rise” scheme is proposed and experimentally validated using a new concept of cascade domino lithography. In this report, we successfully establish a controllable lithography method of making extremely sharp bowtie nanoantennas with sub-1 nm radius of curvature reaching the size of a gold nanocluster as well as single-digit-nanometer gaps between such sharp tips. In addition, a proof-of-concept application of surface enhanced Raman spectroscopy is demonstrated along with rigorous full-wave electromagnetic simulations and numerical analysis. This control of falling nanostructures opens up an unexplored gateway towards conquering the limitations of experimentally exploring the realm of plasmonics down to the sub-nanometer regime.

We investigated the photophysical interactions between CdSe/CdS quantum dots (QDs) and a conjugated polymer (CP, P3HT). The photoluminescence intensity of P3HT in the QDs/P3HT hybrid system is sign...

Chiral plasmonic nanostructures have opened up unprecedented opportunities in optical applications. We present chirality evolution in nanoparticles focusing on the crystallographic aspects and elucidate key parameters for chiral structure formation. From a detailed understanding of chirality formation, we achieved a morphology (432 Helicoid IV) of three-dimensionally controlled chiral plasmonic nanoparticles based on the rhombic dodecahedral shape. The role of the synthesis parameters, seed, cysteine, cetyltrimethylammonium bromide and ascorbic acid on chiral formation are studied, and based on this understanding, the systematic control of the chiral structure is presented. The relation between the modulated chiral structure factors and optical response is further elucidated by electromagnetic simulation. Importantly, a new optical response is achieved by assembling chiral nanoparticles into a film. This comprehensive study of chiral nanoparticles will provide valuable insight for the further development of diverse chiral plasmonic nanostructures with fascinating properties., Chirality of amino acids can be transferred to the high index plane of gold nanoparticles, resulting in chiral plasmonic nanoparticles called the 432 Helicoid series. Here, the authors present a 432 Helicoid IV and describe a systematic approach to modulate the chirality of single particles by controlling the kinetics.

The hybridised resonances between Mie-scatterers and lattice resonances, i.e. quasi-guided mode resonances, are investigated. The scattering of the Mie-resonators is improved by the first order of transmitted diffracted light which is coupled to the lattice formed by the Mie-resonators. The conditions of coupling are dependent on the refractive index of the substrate and the effective refractive index of the unit cell of the resonators. Based on the momentum matching conditions, the cut-off wavelength of coupling and the amount of the amplification can be controlled. As a proof-of-concept application of this framework, gallium nitride metasurfaces are designed to produce metasurfaces that display structural colour. Palettes of full spectral colour and gradients are successfully demonstrated. The hue of the colour can be controlled by changing the periodicity of the unit cell at a fixed filling ratio of Mie-scatterer radius to unit cell periodicity, since the increase in periodicity redshifts the cut-off wavelength of the lattice resonance conditions, identified as the Rayleigh anomaly. The brightness of the colour can be tuned by adjusting the filling ratio of the unit cell. Consequently, the proposed framework may provide a fundamental guideline to design spectral filters made up of low-index Mie-scatterers for various applications.

We investigated the photophysical interaction between a conjugated polymer (CP) and a plasmonic gold nanoparticle (Au NP) using transient absorption spectroscopy. We prepared a hybrid system contai...

Conventional multicolor metaholograms suffer from the fundamental limitations of low resolution and irreducible noise because the unit structure functionality is still confined to a single wavelength. Here, we propose wavelength-decoupled metasurfaces that enables to control chromatic phase responses independently in a full range from 0 to 2π for each wavelength. The propagation phase associated with the geometric phase of rectangular dielectric nanostructures plays a critical role to embed a dual phase response into a single nanostructure. A multicolor metahologram is also demonstrated to verify the feasibility of our method that breaks through the fundamental constraints of conventional multicolor metaholograms. Our approach can be extended to achieve complete control of chromatic phase responses in the visible for general dual-wavelength diffractive optical elements. Conventional multicolour metaholograms suffer from inherently low resolution and irreducible noise due to the single phase response of each unit structure. Here, a wavelength-decoupled multicolour metahologram is demonstrated overcoming the existing problems by a dual phase response in a single nanostructured unit.

Recent introduction of data-driven approaches based on deep-learning technology has revolutionized the field of nanophotonics by allowing efficient inverse design methods. In this paper, a simultaneous inverse design of materials and structure parameters of core-shell nanoparticles is achieved for the first time using deep learning of a neural network. A neural network to learn the correlation between the extinction spectra of electric and magnetic dipoles and core-shell nanoparticle designs, which include material information and shell thicknesses, is developed and trained. We demonstrate deep-learning-assisted inverse design of core-shell nanoparticles for (1) spectral tuning electric dipole resonances, (2) finding spectrally isolated pure magnetic dipole resonances, and (3) finding spectrally overlapped electric dipole and magnetic dipole resonances. Our finding paves the way for the rapid development of nanophotonics by allowing a practical utilization of deep-learning technology for nanophotonic inverse design.

Surface-enhanced circular dichroism (SECD) of chiral molecules adsorbed on plasmonic nanostructures can substantially enhance chiroptical molecular signals by several orders, which is otherwise very weak to be directly measured. Several mechanisms were proposed to explain this extreme enhancement, but the exact mechanism is still controversial. We investigate strong higher-order multipole contribution to SECD near plasmonic nanostructures using the superposition T-matrix method and discuss how 3-dimensional full-field simulations implementing a homogeneous chiral medium have succeeded in the reconstruction of the extreme enhancement. We also discuss how theoretical studies modeling chiral molecules based on dipole approximation have failed to reconstruct the extreme enhancement and show that SECD enhancement of such chiral dipoles is directly governed by optical chirality enhancement. In addition, strong multipolar transitions in subwavelength chiral plasmonic nanoparticles are discussed based on the T-matrix. This work reviews theoretical frameworks describing chiral molecules, demonstrates significant contribution of a multipolar transition on the extreme SECD enhancement near plasmonic nanostructures, and emphasizes the importance of a multipolar transition in chiral nearfield interaction.

We demonstrate phase-matched second-harmonic generation (SHG) from three-dimensional metamaterials consisting of stacked metasurfaces. To achieve phase matching, we utilize a novel mechanism based on phase engineering of the metasurfaces at the interacting wavelengths, facilitating phase-matched SHG in the unconventional backward direction. By stacking up to five metasurfaces, we obtain the expected factor of 25 enhancement in SHG efficiency. Our results motivate further investigations to achieve higher conversion efficiencies also with more complex wavefronts., Comment: 5 pages, 3 figures, supplementary material

Mie scatterer resonantly scatters when wavelength of incident light is similar to the size of the scatterer. The scattering of Mie resonator can be analyzed using multipole decomposition; silicon nanostructure has multipole scattering modes in visible regime. When the Mie scatterers are arrayed, the scattering response can be greatly amplified. To properly design array of Mie scatterer, i.e. metasurface, the hybridization of radiation mode of scatterer and lattice effect, i.e. guided-mode resonance (GMR), must be understood. Herein, we would like to provide the scattering mechanisms behind the hybridization between individual scattering mode and lattice effect, and use them to realize gradient structural coloration by silicon-based metasurface. We believe that a solid understanding of the coupling between individual Mie resonators and the lattice resonances can be a strong basis for designing planar spectral filters.

Light-matter interactions involving structured optical field (SOF) and meta-atoms have been recently investigated. SOF allows a large degree-of-freedom in the interaction, and includes vortex beams with helical wavefront, cylindrical vector beams with spatially inhomogeneous polarization, and non-diffracting Bessel beams. Meta-atoms even further extend the degree-of-freedom. Therefore, accurate and efficient description of both SOFs and arbitrary meta-atoms is required to study this problem, for which multipole approach can be a versatile framework. Here, we discuss description of SOFs and their implementation into multipole approach, and demonstrate dichroisms involving chiral meta-atoms and SOFs with spatially inhomogeneous phase and polarization distributions.

In this abstract, I will discuss our efforts in realizing ultra-sharp nanoantennas with radius of curvature of 1 nm and 5 nm nanogap for extreme photon squeezing applications. Firstly, we propose an unconventional nanolithography technique called cascade domino lithography (CDL) to realize such sharp tip structures. By controlling collapse of micro/nanopillar photoresist structures, diverse plasmonic nanogap structures or single-digit nanometer scale structures can be realized, which are not obtainable with conventional nanofabrications. Secondly, we analyze the optical characteristics of sharp bowtie nanoantennas by using numerical simulations and near/far-field experiments. For instances, an extreme field localization and enhancement are verified by finite-difference time-domain (FDTD) simulations along with near-field scanning optical microscopy (NSOM) measurement, nonlinear spectroscopy and surface-enhanced Raman spectroscopy (SERS).

Recent advancements in nano- and micro-fabrication technology have allowed the realization of artificial structured materials with strong electromagnetic chirality, far-exceeding natural chiral materials. This chapter categorizes the fabrication methods for realizing chiral structures based on the feature sizes, which closely relates to the operating wavelengths. Conventional top-down and bottom-up approaches are discussed along with their respective advantages and disadvantages, and the recently developed unconventional fabrication methods are also provided. Additionally, the chiral responses of the fabricated structures are briefly introduced. This chapter will contribute to the understanding of possible chiral structure designs and help to develop further fabrication methods for improving chiroptical activity.

Interactions between structured optical fields (SOFs) and meta-atoms have been intensively studied, and stimulated by recent advancements on the generation of SOFs and on the synthesis of exotic meta-atoms. Multipole expansion is an efficient and accurate theoretical framework for studying such problems. In this work, explicit expressions of SOFs and their beam-shape coefficients are provided, and their properties are also briefly discussed; the considered SOFs include Laguerre-Gaussian (LG) beams, tightly-focused LG beams, Bessel beams, and cylindrical vector beams. Using the multipole expansion, selective excitations of multipolar resonances of a sphere is discussed. In addition, angular momentum dichroisms of a chiral sphere and an anisotropically chiral meta-atom are calculated to demonstrate selective excitation of multipoles with the desired order, parity, and orientation using engineered SOFs with angular momentum.

Hybrid materials in optoelectronic devices can provide synergistic effects that complementarily enhance the properties of each component. Here, flexible high-performance graphene hybrid photodetectors (PDs) are developed by introducing gold nanostars (GNSs) and perovskites for strong light trapping with hot electron transfer and efficient light harvesting characteristics, respectively. While pristine graphene PDs do not exhibit discernible photodetection properties due to the very low photon absorption and ultrafast charge carrier recombination, graphene PDs functionalized with GNSs and a densely covered perovskite layer exhibit outstanding photoresponsive properties with a photoresponsivity (R) of 5.90 × 104 A W−1 and a specific detectivity of 1.31 × 1013 Jones, the highest values among those reported for perovskite-functionalized graphene PDs thus far. Moreover, we fabricated a flexible 10 × 10 PD array that shows well-resolved spatiotemporal mapping of light signals with excellent operational and mechanical stabilities at a bending radius down to 3 mm and in repeated bending tests for over 1000 cycles. Comprehensive analyses using finite-difference time-domain (FDTD) theoretical calculations, scanning near-field optical microscopy, and photoluminescence mapping reveal the effective light trapping effect of GNSs and the charge carrier transfer between the perovskite and graphene. This work provides a new design platform for flexible and high-performance photodetection systems. Flexible photodetectors that convert light into electric signals for applications including low-light photography can be improved using star-shaped flecks of gold. Single-atom thin graphene sheets have proven useful in many bendable photodetectors due to their favorable mechanical and electronic properties. South Korean researchers led by Hyunhyub Ko from the Ulsan National Institute of Science and Technology and Joon Hak Oh at Seoul National University have now developed a technique to improve graphene’s response to light. By tweaking a typical nanoparticle synthesis method using a sulfur-based buffering agent, the team produced gold nanostars that trap light using localized field-enhanced regions around their spiky tips. Prototype devices, prepared by putting nanostar-coated graphene electrodes onto plastic substrates, could be flexed thousands of times while retaining sufficient light sensitivity for imaging purposes. Flexible high-performance hybrid graphene photodetectors have been developed by introducing both perovskite materials and gold nanostars. The developed photodetectors exhibit significantly enhanced optoelectronic performances due to the synergistic effects of hybrid system including high light absorption of perovskites and strong plasmonic effects of gold nanostars with high mechanical stability, which extends the range of their practical applications.

Metasurfaces made up of subwavelength arrays of Mie scatterers can be engineered to control the optical properties of incident light. The hybridization of the fundamental Mie resonances with lattice resonances greatly enhances the scattering cross-section of individual Mie scatterers. Through careful design of the locations of these hybridized modes using two differently engineered hydrogenated amorphous silicon nanorods, we numerically calculate and experimentally fabricate two examples of full color printing; one with spectral colors comparable to the Adobe RGB gamut, and another with gradients of color. We identify and characterize the mechanisms behind each and provide a framework that can be used to design any all-dielectric metasurfaces of subwavelength Mie scatterers for spectral modulation.

The capillary force effect is one of the most important fabrication parameters that must be considered at the micro/nanoscale because it is strong enough to deform micro/nanostructures. However, the deformation of micro/nanostructures due to such capillary forces (e.g., stiction and collapse) has been regarded as an undesirable and uncontrollable obstacle to be avoided during fabrication. Here, we present a capillary-force-induced collapse lithography (CCL) technique, which exploits the capillary force to precisely control the collapse of micro/nanostructures. CCL uses electron-beam lithography, so nanopillars with various shapes can be fabricated by precisely controlling the capillary-force-dominant cohesion process and the nanopillar-geometry-dominant collapse process by adjusting the fabrication parameters such as the development time, electron dose, and shape of the nanopillars. CCL aims to achieve sub-10-nm plasmonic nanogap structures that promote extremely strong focusing of light. CCL is a simple and straightforward method to realize such nanogap structures that are needed for further research such as on plasmonic nanosensors. An innovative technique—capillary-force-induced collapse lithography (CCL)—has been developed to easily fabricate plasmonic nano-gap structures, which with a nano-gap of

Chirality arises universally across many different fields. Recent advancements in artificial nanomaterials have demonstrated chiroptical responses that far exceed those found in natural materials. Chiroptical phenomena are complicated processes that involve transitions between states with opposite parities, and solid interpretations of these observations are yet to be clearly provided. In this review, we present a comprehensive overview of the theoretical aspects of chirality in light, nanostructures, and nanosystems and their chiroptical interactions. Descriptions of observed chiroptical phenomena based on these fundamentals are intensively discussed. We start with the strong intrinsic and extrinsic chirality in plasmonic nanoparticle systems, followed by enantioselective sensing and optical manipulation, and then conclude with orbital angular momentum-dependent responses. This review will be helpful for understanding the mechanisms behind chiroptical phenomena based on underlying chiral properties and useful for interpreting chiroptical systems for further studies., Towards an extended understanding of chiroptical phenomena Strengthening the theoretical understanding of chirality is necessary for developing applications based on its phenomena. Junsuk Rho of Korea’s Pohang University of Science and Technology (POSTECH) reviewed with colleagues the theoretical aspects of chirality, a symmetry property that describes mirror-image objects or systems that cannot be superimposed. Chiral materials have attracted much attention due to their interesting interactions. Scientists are familiar with how geometrically chiral objects and systems interact with light. However, such ‘chiroptical effects’ can also be found in achiral systems, Rho and his colleagues explain. Also, globally achiral light can be locally chiral near nanostructures. Scientists need to extend their concepts and theoretical understandings of chiroptical systems in order to be able to further develop applications based on their phenomena, such as in metamaterials, sensing, spintronics and stereochemistry.

Surface-enhanced spectroscopy (SES) is a consequence of extreme electromagnetic fields and chemical interactions near a surface. SES is highly sensitive and selective and has been exploited...

Understanding chirality, or handedness, in molecules is important because of the enantioselectivity that is observed in many biochemical reactions 1 , and because of the recent development of chiral metamaterials with exceptional light-manipulating capabilities, such as polarization control2-4, a negative refractive index 5 and chiral sensing 6 . Chiral nanostructures have been produced using nanofabrication techniques such as lithography 7 and molecular self-assembly8-11, but large-scale and simple fabrication methods for three-dimensional chiral structures remain a challenge. In this regard, chirality transfer represents a simpler and more efficient method for controlling chiral morphology12-18. Although a few studies18,19 have described the transfer of molecular chirality into micrometre-sized helical ceramic crystals, this technique has yet to be implemented for metal nanoparticles with sizes of hundreds of nanometres. Here we develop a strategy for synthesizing chiral gold nanoparticles that involves using amino acids and peptides to control the optical activity, handedness and chiral plasmonic resonance of the nanoparticles. The key requirement for achieving such chiral structures is the formation of high-Miller-index surfaces ({hkl}, h ≠ k ≠ l ≠ 0) that are intrinsically chiral, owing to the presence of 'kink' sites20-22 in the nanoparticles during growth. The presence of chiral components at the inorganic surface of the nanoparticles and in the amino acids and peptides results in enantioselective interactions at the interface between these elements; these interactions lead to asymmetric evolution of the nanoparticles and the formation of helicoid morphologies that consist of highly twisted chiral elements. The gold nanoparticles that we grow display strong chiral plasmonic optical activity (a dis-symmetry factor of 0.2), even when dispersed randomly in solution; this observation is supported by theoretical calculations and direct visualizations of macroscopic colour transformations. We anticipate that our strategy will aid in the rational design and fabrication of three-dimensional chiral nanostructures for use in plasmonic metamaterial applications.

We prepared a high-density array of “accordion-like” plasmonic silver nanorods over a large area (2.5 × 2.5 cm2) that exhibited multiple electromagnetic responses to visible and near-infrared (NIR) wavelengths. This array of “accordion-like” silver nanorods was fabricated by confining the lamellae-forming polystyrene-block-poly (methyl methacrylate) copolymer (PS-b-PMMA) inside the cylindrical pores of an aluminum oxide (AAO) template grafted with thin neutral brush layers. PS and PMMA lamellar nanodomains with sizes of 15 nm were alternatively stacked along the nanorod direction. After the AAO template was removed, a 5-nm-thick layer of silver was thermally deposited on only the PS nanodomains. Owing to the multiple resonances exhibited in the visible and NIR regimes, the array could be used for multi-analyte detection. Furthermore, this concept of fabricating sophisticated nanoscale architectures by utilizing block copolymer self-assembly and incorporating plasmonic metals into one nanodomain could be applied to realize large-scale metamaterials that function under visible and NIR wavelengths. A simple technique for creating large array of nanorods that manipulate both visible and near-infrared light has been devised by researchers in South Korea. Metal nanostructures can dramatically influence light. These so-called plasmonic effects usually only occur at specific wavelengths when the light’s frequency matches the natural collective oscillation of surface electrons. The resonant wavelength depends on the dimensions of the nanostructure. Jin Kon Kim, Junsuk Rho, and co-workers from Pohang University of Science and Technology (POSTECH) fabricated nanorods that combine many metal nanostructures of differing dimensions and support multiple resonances. Their structures comprised a stack of alternating layers of polystyrene and poly(methylmethacylate). The outer edges of the polystyrene layers were coated in silver, making the nanorods look like tiny accordions. Arrays of these structures covering several square centimeters were constructed using block copolymer self-assembly. A high density of “accordion-like” silver nanorod array over a large area (~cm2) was fabricated by confining lamellar-forming polystyrene-block-poly (methyl methacrylate) copolymer (PS-b-PMMA) inside cylindrical pores of aluminum oxide (AAO) template grafted by thin neutral brush layers. After removing the AAO template, a 5 nm thick layer of silver was thermally deposited on only PS nanodomains. Owing to combination of hemispherical head and side silver rings, multiple resonances exhibited in the visible and NIR regimes. This sophisticated fabrication utilizing block copolymer self-assembly could be applied to multi-analyte detection and realization of large-scale metamaterials working at visible and NIR wavelengths.