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This study introduces a novel nanogap‐enhanced plasmonic absorber (NEPA) structure generated using the Gray–Scott algorithm. Finite‐difference time‐domain simulations analyzed NEPA's optical properties, varying top pattern thickness from 10 to 300 nm. The simulation results demonstrate exceptional broadband absorption, with rates exceeding 60% across the 90–300 nm thickness range and reaching a peak of 96.73% at 160 nm. The nanogap‐mediated plasmonic nanomaze array exhibits multiple resonance features and complex electric field distributions due to various plasmonic modes. The nearly uniform spacing of the nanomaze pattern maintains consistent plasmonic properties. This innovative approach shows great potential for enhancing plasmonic devices, with applications in solar cells, photodetectors, surface‐enhanced Raman spectroscopy, metamaterials, imaging, energy harvesting, and nanoantennas. Our research advances nanophotonics, offering new possibilities for high‐efficiency optical and optoelectronic devices across various applications. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures (PNs) have transformed nanophotonics by offering control over electromagnetic waves. Although innovative structural designs have demonstrated PNs' potential, significant fabrication challenges, including the precise alignment of heterogeneous materials, remain. Using chloroform and pre‐UV exposure (PUVE) to enhance adhesion at the metal‐dielectric interface (MDI) addresses these challenges. PUVE preserves plasmon resonance in the MDI, ensuring high performance without compromising structural integrity. Through an annealing process, PUVE strengthens van der Waals bonds, ensuring chloroform molecules remain on the Ag surface during chloroform residue removal, allowing: i) stable preservation of the Ag thin film on the PNs during stripping; and ii) the formation of chloroform‐mediated heterogeneous bonding (CMHB) using energy supplied by UV‐nanoimprint lithography (UV‐NIL). This approach enables PNs' scalable fabrication with enhanced adhesion properties, while CMHB increases adhesion between the UV‐curable resin and Ag, offering scalability to large‐area applications with UV‐NIL. The structural morphology and chemical properties of the fabricated PNs are analyzed using scanning electron microscopy, atomic force microscopy, energy‐dispersive spectroscopy, and X‐ray photoelectron spectroscopy. These PNs demonstrate potential in CCD filters, enhancing optical signal amplification for real‐time imaging at the 785 nm band. This robust fabrication method advances PNs' performance and scalability, advancing nanophotonics and related applications. [ABSTRACT FROM AUTHOR]

Quasi‐3D plasmonic nanostructures are in high demand for their ability to manipulate and enhance light‐matter interactions at subwavelength scales, making them promising building blocks for diverse nanophotonic devices. Despite their potential, the integration of these nanostructures with optical sensors and imaging systems on a large scale poses challenges. Here, a robust technique for the rapid, scalable, and seamless replication of quasi‐3D plasmonic nanostructures is presented straight from their production wafers using a microbubble process. This approach not only simplifies the integration of quasi‐3D plasmonic nanostructures into a wide range of standard and custom optical imaging devices and sensors but also significantly enhances their imaging and sensing performance beyond the limits of conventional methods. This study encompasses experimental, computational, and theoretical investigations, and it fully elucidates the operational mechanism. Additionally, it explores a versatile set of options for outfitting nanophotonic devices with custom‐designed plasmonic nanostructures, thereby fulfilling specific operational criteria. [ABSTRACT FROM AUTHOR]

Multivariate analysis applied in biosensing greatly improves analytical performance by extracting relevant information or bypassing confounding factors such as nonlinear responses or experimental errors and noise. Plasmonic sensors based on various light coupling mechanisms have shown impressive performance in biosensing by detecting dielectric changes with high sensitivity. In this study, gold nanodiscs are used as metasurface in a Kretschmann setup, and a variety of features from the reflectance curve are used by machine learning to improve sensing performance. The nanostructures of the metasurface generate new plasmonic features, apart from the typical resonance that occurs in the classical Kretschmann mode of a gold thin film, related to the evanescent field beyond total internal reflection. When the engineered metasurface is integrated into a microfluidic chamber, the device provides additional spectral features generated by Fresnel reflections at all dielectric interfaces. The increased number of features results in greatly improved detection. Here, multivariate analysis enhances analytical sensitivity and sensor resolution by 200% and more than 20%, respectively, and reduces prediction errors by almost 40% compared to a standard plasmonic sensor. The combination of plasmonic metasurfaces and Fresnel reflections thus offers the possibility of improving sensing capabilities even in commonly available setups. [ABSTRACT FROM AUTHOR]

Self-assembling of plasmonic nanoparticles into an oligomer can produce optical nanoantennas with resonant magnetic responses, which constitutes a promising platform to study magnetic light-matter interactions at the nanoscale. However, these self-assembled magnetic nanostructures typically feature a flat-lying geometric configuration, giving rise to out-of-plane magnetic dipole (MD) moments that cannot couple to the far-field light efficiently. Herein, we propose a new geometric configuration of plasmonic nanoantennas to realize in-plane MD responses. This is achieved by elegantly coupling a plasmonic nanoparticle oligomer to one or more adjacent metal mirrors, virtually forming a vertically standing nanoparticle tetramer or trimer, yet with in-plane MD moments. We verified this design strategy by numerically simulating the resonance responses of three typical mirror-coupled nanostructures, all exhibiting pronounced resonant MD characters. Furthermore, optical magnetic emitters can be readily coupled to these plasmonic nanoantennas and gain an emission enhancement of two orders of magnitude while simultaneously featuring a high emission directionality (collection efficiency up to ∼ 70 % evaluated with common microscopy optics). We believe these mirror-enabled magnetic nanoantennas could lead to novel nanophotonic devices fully exploiting the magnetic nature of light. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures can enhance the performance of photodetectors (PDs) owing to their amplification effect in light absorption, leading to overcoming the inherent properties of the photoactive layer. Herein, hierarchical plasmonic nanopatterns have been prepared and used for high‐performance flexible perovskite PDs. The developed hierarchical nanostructures, featuring nanoposts on cross‐nanograting patterns, exhibit a notably enhanced light trapping effect compared to hierarchical nanostructures based on a unidirectional simple nanograting structure. Moreover, hierarchical pattern‐based perovskite PDs show a photoresponsivity of 580 mA W−1 and a specific detectivity of 3.2 × 1012 Jones, which are 420% and 990% higher than those of perovskite PDs without plasmonic nanostructures, respectively. Furthermore, a flexible 10 × 10 PD array has been developed, which enables the accurate mapping of light signals with exceptional operational and mechanical stabilities, under a bending radius as small as 8 mm and after undergoing more than 1000 bending cycles. Comprehensive analyses using finite‐difference time‐domain calculations and photoluminescence mapping reveal the effective light trapping effect of hierarchical plasmonic patterns in the perovskite layers. This work provides an efficient approach to achieve high‐performance perovskite optoelectronic devices. [ABSTRACT FROM AUTHOR]

Enriching the library of chiral plasmonic structures is of significant importance in advancing their applicability across diverse domains such as biosensing, nanophotonics, and catalysis. Here, employing triangle nanoplates as growth seeds, we synthesized a novel class of chiral-shaped plasmonic nanostructures through a wet chemical strategy with dipeptide as chiral inducers, including chiral tri-blade boomerangs, concave rhombic dodecahedrons, and nanoflowers. The structural diversity in chiral plasmonic nanostructures was elucidated through their continuous morphological evolution from two-dimensional to three-dimensional architectures. The fine-tuning of chiroptical properties was achieved by precisely manipulating crucial synthetic parameters such as the amount of chiral molecules, seeds, and gold precursor that significantly influenced chiral structure formation. The findings provide a promising avenue for enriching chiral materials with highly sophisticated structures, facilitating a fundamental understanding of the relationship between structural nuances and chiroptical properties. [ABSTRACT FROM AUTHOR]

Circular dichroism (CD) is a significant optical response of chiral plasmonic nanostructures, with extensive applications in chiral sensing, biological detection, and negative refractive index media. In this study, a substantial enhancement of CD signal is achieved by embedding gold nanorod into planar gold L-shaped nanohole arrays. The structural surface charge distribution revealed that electric and magnetic resonance modes are generated under different circularly polarized lights at the same resonance wavelength. The enhanced CD signals originate from stronger magnetic resonance on L-shaped films and embedded nanorod under right circularly polarized light. Moreover, the CD effect of the nanostructure could be controlled by adjusting the relative positioning, aspect ratio of the embedded nanorod, and the period of the array. To further extend the applications of the nanostructure, the relationship between wavelength and refractive index is explored. These results offer novel insights into the design and manipulation of planar chiral materials with substantial CD and also expand the application of chiral structures in refractive index sensors. [ABSTRACT FROM AUTHOR]

Abstract Quasi‐3D plasmonic nanostructures are in high demand for their ability to manipulate and enhance light‐matter interactions at subwavelength scales, making them promising building blocks for diverse nanophotonic devices. Despite their potential, the integration of these nanostructures with optical sensors and imaging systems on a large scale poses challenges. Here, a robust technique for the rapid, scalable, and seamless replication of quasi‐3D plasmonic nanostructures is presented straight from their production wafers using a microbubble process. This approach not only simplifies the integration of quasi‐3D plasmonic nanostructures into a wide range of standard and custom optical imaging devices and sensors but also significantly enhances their imaging and sensing performance beyond the limits of conventional methods. This study encompasses experimental, computational, and theoretical investigations, and it fully elucidates the operational mechanism. Additionally, it explores a versatile set of options for outfitting nanophotonic devices with custom‐designed plasmonic nanostructures, thereby fulfilling specific operational criteria.

Bimetallic core‐shell nanoparticles (NPs) possessing a synergetic coupling of plasmonic and catalytic metals have emerged as promising prototypes for efficient plasmon‐driven photocatalysis. Here, Au@AuPd core‐shell NPs composed of Au core NP and ultrathin AuPd shell are introduced to acquire improved light utilization efficiency in photocatalytic selective oxidation. With systematical control of the composition of the ultrathin alloy shell, it reveals that the Au@AuPd core‐shell NPs with 10 at% Pd (in the single‐atom alloy regime) is an effective nanostructure capable of maximizing the quantum yield of plasmon‐induced light absorption and optimizing the surface electronic structure for catalytic reactions. This controlled system provides new insights into shell engineering for enhancing photocatalytic performance via the regulation of energy funneling processes in core‐shell nanocatalysts. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures can enhance the performance of photodetectors (PDs) owing to their amplification effect in light absorption, leading to overcoming the inherent properties of the photoactive layer. Herein, hierarchical plasmonic nanopatterns have been prepared and used for high‐performance flexible perovskite PDs. The developed hierarchical nanostructures, featuring nanoposts on cross‐nanograting patterns, exhibit a notably enhanced light trapping effect compared to hierarchical nanostructures based on a unidirectional simple nanograting structure. Moreover, hierarchical pattern‐based perovskite PDs show a photoresponsivity of 580 mA W−1 and a specific detectivity of 3.2 × 1012 Jones, which are 420% and 990% higher than those of perovskite PDs without plasmonic nanostructures, respectively. Furthermore, a flexible 10 × 10 PD array has been developed, which enables the accurate mapping of light signals with exceptional operational and mechanical stabilities, under a bending radius as small as 8 mm and after undergoing more than 1000 bending cycles. Comprehensive analyses using finite‐difference time‐domain calculations and photoluminescence mapping reveal the effective light trapping effect of hierarchical plasmonic patterns in the perovskite layers. This work provides an efficient approach to achieve high‐performance perovskite optoelectronic devices.

Plasmonic materials exhibit localized plasmon resonances that collect light and concentrate electric fields around nanostructures. The field enhancements are useful for applications such as spectroscopy, catalysis, and photodetection. Electric field enhancements are dependent on the materials, geometric designs, and positioning of nanostructures. Plasmonic dimers are especially effective to concentrate electric fields between nanostructures, and there is significant interest to develop nanofabrication strategies to control interparticle distances with subnanometer precision for arbitrary designs. In this work, we investigate arrays of interconnected plasmonic dimers with sub-10 nm nanogaps achieved by Cu area-selective atomic layer deposition (ALD). Nanostructures are made by conventional nanofabrication methods and subsequently coated with conformal layers of Cu to control the interparticle distances. Au and Pd layers are used to activate Cu deposition for homodimer and heterodimer combinations with and without interconnects. Optical extinction measurements before and after growth experiments show how plasmon resonances change when Cu layers expand nanostructures and reduce nanogaps formed between dimer pairs. Finite difference time domain simulations are used to model experiments and study how modifications of nanostructure sizes, thicknesses, and shapes affect plasmonic properties. Our findings show that Cu ALD can reduce nanogaps below 10 nm for both interconnected and unconnected nanorods and that interconnected plasmonic dimers have optical properties similar to unconnected dimers. Moreover, the ALD process can scale to large arrays of nanostructures. Results are promising for achieving subnanometer control of interparticle distances for devices that combine electrical and optical functions with intense electric fields generated by localized surface plasmon resonances. [ABSTRACT FROM AUTHOR]

Human existence and societal growth are both dependent on the availability of clean and fresh water. Photocatalysis is a type of artificial photosynthesis that uses environmentally friendly, long-lasting materials to address energy and environmental issues. There is currently a considerable demand for low-cost, high-performance wastewater treatment equipment. By changing the structure, size, and characteristics of nanomaterials, the use of nanotechnology in the field of water filtration has evolved dramatically. Semiconductor-assisted photocatalysis has recently advanced to become among the most promising techniques in the fields of sustainable energy generation and ecological cleanup. It is environmentally beneficial, cost-effective, and strictly linked to the zero waste discharge principle used in industrial effluent treatment. Owing to the reduction or removal of created unwanted byproducts, the green synthesis of photoactive nanomaterial is more beneficial than chemical synthesis approaches. Furthermore, unlike chemical synthesis methods, the green synthesis method does not require the use of expensive, dangerous, or poisonous ingredients, making it a less costly, easy, and environmental method for photocatalyst synthesis. This work focuses on distinct greener synthesis techniques utilized for the production of new photocatalysts, including metals, metal doped-metal oxides, metal oxides, and plasmonic nanostructures, including the application of artificial intelligence and machine learning to the design and selection of an innovative photocatalyst in the context of energy and environmental challenges. A brief overview of the industrial and environmental applications of photocatalysts is also presented. Finally, an overview and recommendations for future research are given to create photocatalytic systems with greatly improved stability and efficiency. [ABSTRACT FROM AUTHOR]

Abstract Bimetallic core‐shell nanoparticles (NPs) possessing a synergetic coupling of plasmonic and catalytic metals have emerged as promising prototypes for efficient plasmon‐driven photocatalysis. Here, Au@AuPd core‐shell NPs composed of Au core NP and ultrathin AuPd shell are introduced to acquire improved light utilization efficiency in photocatalytic selective oxidation. With systematical control of the composition of the ultrathin alloy shell, it reveals that the Au@AuPd core‐shell NPs with 10 at% Pd (in the single‐atom alloy regime) is an effective nanostructure capable of maximizing the quantum yield of plasmon‐induced light absorption and optimizing the surface electronic structure for catalytic reactions. This controlled system provides new insights into shell engineering for enhancing photocatalytic performance via the regulation of energy funneling processes in core‐shell nanocatalysts.

Plasmonic nanostructures capable of broadband light trapping and field enhancement have promising applications in a wide range of fields. This study presents a platform for broadband, polarization‐independent field enhancement in the visible regime through the use of width‐graded nanocavities in a bullseye configuration. The fabrication procedure utilizes electron beam lithography (EBL) to achieve fine control over the nanocavity geometry and template stripping to enable rapid and low‐cost production. The utility of these devices as substrates for multi‐wavelength surface enhanced Raman spectroscopy (SERS) is demonstrated through molecular detection in a 10 μM solution at two excitation wavelengths. The impact of bullseye geometry on both the broadband spectral response and multi‐wavelength SERS performance is examined. The measured SERS enhancement factor (EF) is shown to depend primarily on the plasmonically active surface area of the device, regardless of the local electromagnetic field strength within the nanocavities. These results highlight not only the utility of the width‐graded bullseye as a broadband platform for SERS and other applications but also provide design guidelines to optimize the enhancement factor and broadband performance of similar devices. [ABSTRACT FROM AUTHOR]

Fluorescent carbon nanodots are a promising nanomaterial for different applications in biophotonics, sensing and optical nanothermometry fields due to their strong fluorescence properties. However, their multi-modal applications are considerably limited, requiring the use of several nanoagents that could solve different tasks simultaneously. In this paper, we report the first experimental results on a facile "green" laser-based synthesis of multi-modal carbon–metallic nanocomposites with tuned optical performance. This simple approach leads to the appearance of finely controlled plasmonic properties in carbon-based nanocomposites whose spectral position is adapted by using an appropriate material. Thus, longer laser ablation provokes 29-fold increase in the absorption intensity of carbon–gold nanocomposites due to the increase in the metal content from 13% (30 s) to 53% (600 s). Despite strong plasmonic properties, the metal presence results in the quenching of the carbon nanostructures' fluorescence (2.4-fold for C-Au NCs and 3.6-fold for C-Ag NCs for 600 s ablation time). Plasmonic nanocomposites with variable metal content reveal a ~3-fold increase in the laser-to-heat conversion efficiency of carbon nanodots matching the temperature range for mild hyperthermia applications. The findings presented demonstrate a facile approach to expanding the properties of chemically prepared semiconductor nanostructures due to the formation of novel semiconductor–metallic nanocomposites using a "green" approach. Together with the ease in control of their performance, it can considerably increase the impact of semiconductor nanomaterials in various photonic, plasmonic and biomedical applications. [ABSTRACT FROM AUTHOR]

Epitaxy is the process of crystallization of monocrystalline layers and nanostructures on a crystalline substrate. It allows for the crystallization of various semiconductor layers on a finite quantity of semiconductor substrates, like GaAs, InP, GaP, InGaP, GaP, and many others. The growth of epitaxial heterostructures is very complicated and requires special conditions and the precise control of the growth temperature, the pressure in the reactor, and the flow of the precursors. It is used to grow epitaxial structures in lasers, diodes, detectors, photovoltaic structures, and so on. Semiconductors themselves are not suitable materials for application in surface-enhanced Raman spectroscopy (SERS) due to poor plasmonic properties in the UV/VIS range caused by missing free electrons in the conduction band due to the existing band gap. A plasmonic material is added on top of the nanostructured pattern, allowing for the formation of mixed photon–plasmon modes called localized surface plasmon-polaritons which stand behind the SERS effect. Typically, gold and silver are used as functional plasmonic layers. Such materials could be deposited via chemical or physical process. Attention has also been devoted to other plasmonic materials, like ones based on the nitrides of metals. The SERS performance of a functional surface depends both on the response of the plasmonic material and the morphology of the underlying semiconductor epitaxial layer. In the context of SERS, epitaxial growth allows for the fabrication of substrates with well-defined 3D nanostructures and enhanced electromagnetic properties. In this work, we described the possible potential plasmonic modification, composed of various coatings such as noble metals, TiN, and others, of well-developed epitaxial nanostructures for the construction of a new type of highly active SERS platforms. This abstract also highlights the role of epitaxial growth in advancing SERS, focusing on its principles, methods, and impact. Furthermore, this work outlines the potential of epitaxial growth to push the boundaries of SERS. The ability to design substrates with tailored plasmonic properties opens avenues for ultralow concentration detection. [ABSTRACT FROM AUTHOR]

This study explores important parameters for achieving a high-level positional control of DNA-nanoparticle hybrid structures by drop-casting onto a pre-structured silicon surface, in which the active adsorption sites were defined using electron beam lithography. By confining the adsorption sites to the scale of the DNA origami, we create multi-dimensional patterns and study the effect of diffusion and hybrid nanostructure concentration in the liquid on site occupation. We also propose a physical diffusion model that highlights the importance of surface diffusion in facilitating the adsorption of hybrid nanostructure onto active sites, particularly for two and one-dimensional adsorption sites. Our study shows prominent results of the hybrid nanostructure's selective adsorption, indicating high adsorption efficiency and precise control over the position, as well as the spatial orientation. We anticipate similar results in related systems, both in terms of different surfaces and similar DNA structures. Overall, our findings offer promising prospects for the development of large-scale nanoarrays on micrometer-scale surfaces with nanometer precision and orientation control. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures are emerging as a promising avenue for nanophotonics due to their extreme light and thermal confinement, ultrafast manipulation processes, and potential uses in device miniaturization. However, their fixed functions have limited their versatility in applications. This review provides an overview of recent switchable plasmonic nanostructure engineering techniques, focusing on methods that provide reversible switchability. Passive optical switching, active structure‐tunable switching, active material‐based switching, and advanced applications, such as multifunctional biomedical sensing, energy harvesting, and dynamic optical devices, are discussed. The specific methods and techniques used to engineer switchable plasmonic nanostructures are also highlighted. By understanding the latest developments and overall trends, this review is expected to help researchers design and fabricate advanced plasmonic nanostructures with unprecedented switchability and versatility for various applications. [ABSTRACT FROM AUTHOR]

Nonlinear optical (NLO) imaging has emerged as a promising plant cell imaging technique due to its large optical penetration, inherent 3D spatial resolution, and reduced photodamage; exogenous nanoprobes are usually needed for nonsignal target cell analysis. Here, we report in vivo, simultaneous 3D labeling and imaging of potato cell structures using plasmonic nanoprobe-assisted multimodal NLO microscopy. Experimental results show that the complete cell structure can be imaged via the combination of second-harmonic generation (SHG) and two-photon luminescence (TPL) when noble metal silver or gold ions are added. In contrast, without the noble metal ion solution, no NLO signals from the cell wall were acquired. The mechanism can be attributed to noble metal nanoprobes with strong nonlinear optical responses formed along the cell walls via a femtosecond laser scan. During the SHG-TPL imaging process, noble metal ions that crossed the cell wall were rapidly reduced to plasmonic nanoparticles with the fs laser and selectively anchored onto both sides of the cell wall, thereby leading to simultaneous 3D labeling and imaging of the potato cells. Compared with the traditional labeling technique that needs in vitro nanoprobe fabrication and cell labeling, our approach allows for one-step, in vivo labeling of plant cells, thus providing a rapid, cost-effective method for cellular structure construction and imaging. [ABSTRACT FROM AUTHOR]

High-index dielectric nanoantennas, which provide an interplay between electric and magnetic modes, have been widely used as building blocks for a variety of devices and metasurfaces, both in linear and nonlinear regimes. Here, we investigate hybrid metal-semiconductor nanoantennas, consisting of a multimode silicon nanopillar core coated with a gold layer, that offer an enhanced degree of control over the mode selection and confinement, and emission of light on the nanoscale exploiting high-order electric and magnetic resonances. Cathodoluminescence spectra revealed a multitude of resonant modes supported by the nanoantennas due to hybridization of the Mie resonances of the core and the plasmonic resonances of the shell. Eigenmode analysis revealed the modes that exhibit enhanced field localization at the gold interface, together with high confinement within the nanopillar volume. Consequently, this architecture provides a flexible means of engineering nanoscale components with tailored optical modes and field confinement for a plethora of applications, including sensing, hot-electron photodetection and nanophotonics with cylindrical vector beams.

Plasmonic nanostructures are emerging as a promising avenue for nanophotonics due to their extreme light and thermal confinement, ultrafast manipulation processes, and potential uses in device miniaturization. However, their fixed functions have limited their versatility in applications. This review provides an overview of recent switchable plasmonic nanostructure engineering techniques, focusing on methods that provide reversible switchability. Passive optical switching, active structure‐tunable switching, active material‐based switching, and advanced applications, such as multifunctional biomedical sensing, energy harvesting, and dynamic optical devices, are discussed. The specific methods and techniques used to engineer switchable plasmonic nanostructures are also highlighted. By understanding the latest developments and overall trends, this review is expected to help researchers design and fabricate advanced plasmonic nanostructures with unprecedented switchability and versatility for various applications.

Localized surface plasmonic resonance (LSPR) provides a unique scheme for light management and has been demonstrated across a large variety of metallic nanostructures. More recently, non-metallic nanostructures of two-dimensional atomic materials and heterostructures have emerged as a promising, low-cost alternative in order to generate strong LSPR. In this paper, a review of the recent progress made on non-metallic LSPR nanostructures will be provided in comparison with their metallic counterparts. A few applications in optoelectronics and sensors will be highlighted. In addition, the remaining challenges and future perspectives will be discussed. [ABSTRACT FROM AUTHOR]

Efficient simulation methods for taking nonlocal effects in nanostructures into account have been developed, but they are usually computationally expensive or provide little insight into underlying physics. A multipolar expansion approach, among others, holds promise to properly describe electromagnetic interactions in complex nanosystems. Conventionally, the electric dipole dominates in plasmonic nanostructures, while higher order multipoles, especially the magnetic dipole, electric quadrupole, magnetic quadrupole, and electric octopole, can be responsible for many optical phenomena. The higher order multipoles not only result in specific optical resonances, but they are also involved in the cross-multipole coupling, thus giving rise to new effects. In this work, we introduce a simple yet accurate simulation modeling technique, based on the transfer-matrix method, to compute higher-order nonlocal corrections to the effective permittivity of 1d plasmonic periodic nanostructures. In particular, we show how to specify the material parameters and the arrangement of the nanolayers in order to maximize or minimize various nonlocal corrections. The obtained results provide a framework for guiding and interpreting experiments, as well as for designing metamaterials with desired dielectric and optical properties. [ABSTRACT FROM AUTHOR]

The homogeneous and ordered coverage of substrate surfaces with nanostructures is still a challenge and is often tackled today, for example, by inkjet printing. In this case, drying effects in printed liquid droplets can lead to undesired pattern formation. Herein, colloidal arrays of poly-N-isopropylacrylamide are used for site-selective self-assembly of gold nanoparticles on large areas. The soft colloids support the drying process of gold nanoparticle dispersion droplets and leave room for capillary convection and Marangoni convection flow. This results in homogenous gold nanoparticle arrays with different shapes after drying, which can be converted into solid gold nanostructures by thermal treatment, paving the way for a simple bottom-up fabrication strategy for highly ordered nanostructure arrays on large areas. [ABSTRACT FROM AUTHOR]

Formation of plasmonic structure in closely packed assemblies of metallic nanoparticles (NPs) is essential for various applications in sensing, renewable energy, authentication, catalysis, and metamaterials. Herein, a surface-enhanced Raman scattering (SERS) substrate is fabricated for trace detection with ultrahigh sensitivity and stability. The SERS substrate is constructed from a simple yet robust strategy through in situ growth patterned assemblies of Au NPs based on a polymer brush templated synthesis strategy. Benefiting from the dense and uniform distribution of Au NPs, the resulting Au plasmonic nanostructure demonstrates a very strong SERS effect, while the outer polymer brush could restrict the excessive growth of Au NPs and the patterned design could achieve uniform distribution of Au NPs. As results, an ultra-low limit of detection (LOD) of 10−15 M, which has never been successfully detected in other work, is determined for 4-acetamidothiophenol (4-AMTP) molecules and the Raman signals in the random region show good signal homogeneity with a low relative standard deviation (RSD) of 7.2%, indicating great sensitivity and reliability as a SERS substrate. The LOD values of such Au plasmonic nanostructures for methylene blue, thiram, and R6G molecules can also reach as low as 10−10 M, further indicating that the substrate has a wide range of applicability for SERS detection. With the help of finite difference time domain simulations (FDTD) calculation, the electric field distribution of the Au plasmonic nanostructures is simulated, which quantitatively matches the experimental observations. Moreover, the Au plasmonic nanostructures show good shelf stability for at least 10 months of storage in an ambient environment, indicating potentials for practical applications. [ABSTRACT FROM AUTHOR]

In this work, we report a study on the effect of the laser-assisted alloying effect on plasmonic properties of Pd and Au-Pd nanostructures using surface-enhanced Raman spectroscopy (SERS). The monometallic and bimetallic nanostructures are formed by nanosecond-laser induced de-wetting and the alloying of pure Pd and bimetallic Au-Pd nanoscale-thick films deposited on a transparent and conductive substrate. The morphological characteristics of the nanostructures were changed by controlling the laser fluence. Then, 4-nitrithiophenol (4-NTP) was used as an adsorbed molecule on the surface of the nanostructures to analyze the resulting SERS properties. A quantitative analysis was reported using the SERS profile properties, such as FWHM, amplitude, and Raman peak position variation. An excellent correlation between the variation of SERS properties and the nanostructures' size was confirmed. The optical enhancement factor was estimated for Pd and Au-Pd nanostructures for the laser fluence (0, 0.5, 0.75, 1, and 1.5 J/cm2). [ABSTRACT FROM AUTHOR]

The hot electron generation in plasmonic nanoparticles is the key to efficient plasmonic photocatalysis. Here, the effect of Tamm states (TSs) at the metal–semiconductor interface on hot electron generation and Landau damping (LD) in metal nanoparticles is studied theoretically for the first time. TSs can lead to resonant hot electron generation and to the LD rate enhanced by several times. The resonant hot electron generation is reinforced by the transition absorption due to the jump of the permittivity at the metal–semiconductor interface. Since electron states in the metal and the quasi‐discrete TS are coupled coherently ("bound state in continuum"), the absorption spectrum of light by electrons has a Fano‐type shape. The results demonstrate clearly the importance of taking into account details of the semiconductor band structure and surface states at the metal–semiconductor interface, including Tamm surface states, for a proper description of the hot carrier generation and LD. The results are in correspondence with earlier experimental works on coherent electron transport and chemical‐induced damping in plasmonic nanostructures. Thus, by judicious selection of semiconductor materials with Tamm surface states one can engineer decay rates and hot carrier production for important applications, such as photodetection and photochemistry. [ABSTRACT FROM AUTHOR]

Under the action of light under the conditions of plasmon resonance, metal nanoparticles induce nanoscale heating. This effect forms the basis for thermoplasmon probing of phase changes occurring in the nanoscale systems whose investigation is the key problem in the modern materials science. Despite an evident simplicity of such an approach, intensive absorption of light by resonance nanostructures does not ensure the desired optical heating in the cases when the thermal conduction of the medium significantly exceeds that of the plasmonic nanostructure. We propose the approach to creation of the controlled heating of plasmonic nanostructures by nanostructuring the thermostat surface, which is demonstrated with the help of the thermoplasmonic metasurface, which is an array of TiN:Si voxels—the vertical system of nanostructures of titanium nitride (TiN) and silicon (Si) on a silicon substrate. The plasmonic nanostructures of TiN play the role of nanoheaters, while varying the height of silicon thermal conductors makes it possible to control the temperature of heating of the voxels at a fixed value of pump intensity owing to the control of heat localization. The possibility of probing phase transitions in the nanoscale systems is demonstrated by an example of thin polymer films with the use of thermoplasmonic metasurface and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Accurate identification of malignant lung lesions is a prerequisite for rational clinical management to reduce morbidity and mortality of lung cancer. However, classification of lung nodules into malignant and benign cases is difficult as they show similar features in computer tomography and sometimes positron emission tomography imaging, making invasive tissue biopsies necessary. To address the challenges in evaluating indeterminate nodules, the authors investigate the molecular profiles of small extracellular vesicles (sEVs) in differentiating malignant and benign lung nodules via a liquid biopsy‐based approach. Aiming to characterize phenotypes between malignant and benign groups, they develop a single‐molecule‐resolution‐digital‐sEV‐counting‐detection (DECODE) chip that interrogates three lung‐cancer‐associated sEV biomarkers and a generic sEV biomarker to create sEV molecular profiles. DECODE capturessEVs on a nanostructured pillar chip, confines individual sEVs, and profiles sEV biomarker expression through surface‐enhanced Raman scattering barcodes. The author utilize DECODE to generate a digitally acquired sEV molecular profiles in a cohort of 33 people, including patients with malignant and benign lung nodules, and healthy individuals. Significantly, DECODE reveals sEV‐specific molecular profiles that allow the separation of malignant from benign (area under the curve, AUC = 0.85), which is promising for non‐invasive characterisation of lung nodules found in lung cancer screening and warrants further clinincal validaiton with larger cohorts. [ABSTRACT FROM AUTHOR]

Structural colors resulting from nanostructured metallic surfaces hold a series of advantages compared to conventional chemical pigments and dyes, such as enhanced durability, tunability, scalability, and low consumption, making them particularly promising for preparing color-tunable devices. However, once these structures are fabricated, they are almost all passive devices with static nanostructures and fixed optical properties, limiting their potential applications. Here, by using a specially designed array of ordered SiO2 nanoholes as a deposition template in conjunction with the traditional reversible metal electrodeposition device (RMED), we propose a tunable reflective surface where the color of the surface can be changed as a function of the thickness of the deposited Ag nanoparticles (AgNPs). Simplified manufacturability and a large range of color tunability are achieved over previous reports by utilizing the SiO2 nanohole template, which allows the direct deposition of AgNPs while forming an array structure of Ag nanocylinders. Besides, a further thematic analysis of the physical mechanism in the proposed structure is conducted. The results show that the structural colors induced by the longitudinal localized surface plasmon resonance (LSPR) mode can be dynamically tuned from brown to purple via increasing the deposition thickness. Additionally, in combination with SiO2 nanohole templates of varying parameters, a full gamut of colors spanning the entire visible spectrum is achieved, revealing the feasibility of utilizing the properties of the LSPR mode for satisfying various color requirements. We believe that this LSPR-based multicolor RMED design will contribute to the development of full color information displays and light-modulating devices. [ABSTRACT FROM AUTHOR]

Plasmonic optical tweezers that stem from the need to trap and manipulate ever smaller particles using non-invasive optical forces, have made significant contributions to precise particle motion control at the nanoscale. In addition to the optical forces, other effects have been explored for particle manipulation. For instance, the plasmonic heat delivery mechanism generates micro- and nanoscale optothermal hydrodynamic effects, such as natural fluid convection, Marangoni fluid convection and thermophoretic effects that influence the motion of a wide range of particles from dielectric to biomolecules. In this review, a discussion of optothermal effects generated by heated plasmonic nanostructures is presented with a specific focus on applications to optical trapping and particle manipulation. It provides a discussion on the existing challenges of optothermal mechanisms generated by plasmonic optical tweezers and comments on their future opportunities in life sciences.

[Display omitted] • Ce doped ZnO-Ag hybrid nanorods were synthesized by thermal decomposition. • UV–vis DRS showed Ag decoration led to decrease in band gap from 3.26 to 3.19 eV. • Ce doped ZnO-Ag nanohybrids exhibited strong catalytic and photocatalytic performance. • Ce doped ZnO-Ag hybrid nanorods decomposed toxic pollutants in 12 min. • Mechanism of photocatalytic action of Ce doped ZnO-Ag nanohybrids is proposed. Designing plasmonic metal–semiconductor hybrid nanostructures for photodecomposition of industrial textile effluent has been considered as a great way to boost the catalytic and photocatalytic capability by promoting effective separation of photoexcited charge carriers. Herein, fabrication of Ag nanoparticles decorated Ce doped ZnO nanostructures were demonstrated via facile wet chemical method. The morphology and structure of the fabricated photocatalysts were analysed using FESEM, XRD and Raman spectroscopy whereas PL, TRPL and UV–vis absorption spectroscopy were employed to examine their optical behaviour. Catalytic response of the synthesized catalysts was studied for 4-NP to 4-AP reduction and the results are more favourable for Ag loaded Ce doped ZnO catalysts and achieved 96.4 % reduction of 4-NP in only 4 min. Photocatalytic measurements showed that higher Ag NP loading onto Ce doped ZnO nanostructures led to superior photodegradation ability over other photocatalysts for the degradation of synthetic dyes and levofloxacin antibiotic. The sunlight driven photodecolorization of harmful synthetic dyes and levofloxacin were studied and efficacy of 97.5, 97.1, 85.1, and 70.9 % were achieved for MG, MB, RhB and MO dyes, respectively in 12 min and 97.2 % efficiency for degradation of levofloxacin was achieved in 20 min of sunlight exposure. Furthermore, the key reactive species was identified and tentative photodegradation process was explained. This work provides an excellent plasmonic-semiconductor catalyst and photocatalyst with good photostability and practical applicability indicating its enormous potential for application in environmental remediation. [ABSTRACT FROM AUTHOR]

Many regions around the world, including the Arabian Peninsula, face a scarcity of freshwater resources and depend heavily on non-renewable energy sources for energy-intensive desalination processes, emphasizing the need for sustainable water treatment methods. To tackle this challenge, solar energy-driven membrane distillation is a promising and compatible solution for desalinating seawater. In this work, a solar-powered photothermal air gap membrane distillation (AGMD) system has been tested to treat brine by utilizing plasmonic-based composite membranes. Polyvinylidene fluoride (PVDF) membranes were prepared by incorporating low-cost zirconium nitride (ZrN) nanoparticles at varying concentrations to facilitate solar energy harvesting. ZrN-modified PVDF composite membranes significantly boost the solar absorption up to 75 % in the wavelength range of 250–800 nm, when compared to pristine PVDF membranes. The composite membranes with 56 % enhancement in porosity resulted in a permeate flux of 0.36 L m−2 h−1 and a rejection rate of ∼99 %. The developed photothermal water treatment system provides a highly effective and scalable solution for water treatment. Moreover, next-generation materials exhibiting photothermal effects have the potential to exploit solar renewable energy for decentralized off-grid desalination by converting sunlight into heat for a unique and favourable water-energy nexus. [Display omitted] [ABSTRACT FROM AUTHOR]

Fluorescent carbon nanodots are a promising nanomaterial for different applications in biophotonics, sensing and optical nanothermometry fields due to their strong fluorescence properties. However, their multi-modal applications are considerably limited, requiring the use of several nanoagents that could solve different tasks simultaneously. In this paper, we report the first experimental results on a facile “green” laser-based synthesis of multi-modal carbon–metallic nanocomposites with tuned optical performance. This simple approach leads to the appearance of finely controlled plasmonic properties in carbon-based nanocomposites whose spectral position is adapted by using an appropriate material. Thus, longer laser ablation provokes 29-fold increase in the absorption intensity of carbon–gold nanocomposites due to the increase in the metal content from 13% (30 s) to 53% (600 s). Despite strong plasmonic properties, the metal presence results in the quenching of the carbon nanostructures’ fluorescence (2.4-fold for C-Au NCs and 3.6-fold for C-Ag NCs for 600 s ablation time). Plasmonic nanocomposites with variable metal content reveal a ~3-fold increase in the laser-to-heat conversion efficiency of carbon nanodots matching the temperature range for mild hyperthermia applications. The findings presented demonstrate a facile approach to expanding the properties of chemically prepared semiconductor nanostructures due to the formation of novel semiconductor–metallic nanocomposites using a “green” approach. Together with the ease in control of their performance, it can considerably increase the impact of semiconductor nanomaterials in various photonic, plasmonic and biomedical applications.

Epitaxy is the process of crystallization of monocrystalline layers and nanostructures on a crystalline substrate. It allows for the crystallization of various semiconductor layers on a finite quantity of semiconductor substrates, like GaAs, InP, GaP, InGaP, GaP, and many others. The growth of epitaxial heterostructures is very complicated and requires special conditions and the precise control of the growth temperature, the pressure in the reactor, and the flow of the precursors. It is used to grow epitaxial structures in lasers, diodes, detectors, photovoltaic structures, and so on. Semiconductors themselves are not suitable materials for application in surface-enhanced Raman spectroscopy (SERS) due to poor plasmonic properties in the UV/VIS range caused by missing free electrons in the conduction band due to the existing band gap. A plasmonic material is added on top of the nanostructured pattern, allowing for the formation of mixed photon–plasmon modes called localized surface plasmon-polaritons which stand behind the SERS effect. Typically, gold and silver are used as functional plasmonic layers. Such materials could be deposited via chemical or physical process. Attention has also been devoted to other plasmonic materials, like ones based on the nitrides of metals. The SERS performance of a functional surface depends both on the response of the plasmonic material and the morphology of the underlying semiconductor epitaxial layer. In the context of SERS, epitaxial growth allows for the fabrication of substrates with well-defined 3D nanostructures and enhanced electromagnetic properties. In this work, we described the possible potential plasmonic modification, composed of various coatings such as noble metals, TiN, and others, of well-developed epitaxial nanostructures for the construction of a new type of highly active SERS platforms. This abstract also highlights the role of epitaxial growth in advancing SERS, focusing on its principles, methods, and impact. Furthermore, this work outlines the potential of epitaxial growth to push the boundaries of SERS. The ability to design substrates with tailored plasmonic properties opens avenues for ultralow concentration detection.

Nonlinear optical (NLO) imaging has emerged as a promising plant cell imaging technique due to its large optical penetration, inherent 3D spatial resolution, and reduced photodamage; exogenous nanoprobes are usually needed for nonsignal target cell analysis. Here, we report in vivo, simultaneous 3D labeling and imaging of potato cell structures using plasmonic nanoprobe-assisted multimodal NLO microscopy. Experimental results show that the complete cell structure can be imaged via the combination of second-harmonic generation (SHG) and two-photon luminescence (TPL) when noble metal silver or gold ions are added. In contrast, without the noble metal ion solution, no NLO signals from the cell wall were acquired. The mechanism can be attributed to noble metal nanoprobes with strong nonlinear optical responses formed along the cell walls via a femtosecond laser scan. During the SHG-TPL imaging process, noble metal ions that crossed the cell wall were rapidly reduced to plasmonic nanoparticles with the fs laser and selectively anchored onto both sides of the cell wall, thereby leading to simultaneous 3D labeling and imaging of the potato cells. Compared with the traditional labeling technique that needs in vitro nanoprobe fabrication and cell labeling, our approach allows for one-step, in vivo labeling of plant cells, thus providing a rapid, cost-effective method for cellular structure construction and imaging.

Abstract Accurate identification of malignant lung lesions is a prerequisite for rational clinical management to reduce morbidity and mortality of lung cancer. However, classification of lung nodules into malignant and benign cases is difficult as they show similar features in computer tomography and sometimes positron emission tomography imaging, making invasive tissue biopsies necessary. To address the challenges in evaluating indeterminate nodules, the authors investigate the molecular profiles of small extracellular vesicles (sEVs) in differentiating malignant and benign lung nodules via a liquid biopsy‐based approach. Aiming to characterize phenotypes between malignant and benign groups, they develop a single‐molecule‐resolution‐digital‐sEV‐counting‐detection (DECODE) chip that interrogates three lung‐cancer‐associated sEV biomarkers and a generic sEV biomarker to create sEV molecular profiles. DECODE capturessEVs on a nanostructured pillar chip, confines individual sEVs, and profiles sEV biomarker expression through surface‐enhanced Raman scattering barcodes. The author utilize DECODE to generate a digitally acquired sEV molecular profiles in a cohort of 33 people, including patients with malignant and benign lung nodules, and healthy individuals. Significantly, DECODE reveals sEV‐specific molecular profiles that allow the separation of malignant from benign (area under the curve, AUC = 0.85), which is promising for non‐invasive characterisation of lung nodules found in lung cancer screening and warrants further clinincal validaiton with larger cohorts.

[Display omitted] • The high catalytic activity of plasmonic Ag-modified AlOOH prepared by the microemulsion method is derived from its high specific surface area, more active surface OH groups, and multi-active adsorption sites relative to other synthetic strategies. • The plasmonic Ag-modified AlOOH has a molecular enrichment effect to the hotspot regions of noble metal nanostructures. • The fabricated SERS-based platform improves the Raman-enhanced properties of Ag achieving high-sensitivity detection of probe molecules with affinity for OH groups and provides experimental basis for further practical detection through the calibration of constructed substrate. Significant breakthroughs have been made in the development of surface-enhanced Raman scattering (SERS) substrates constructed by depositing plasmonic Ag onto nanostructured platforms. AlOOH is widely fabricated using hydrothermal, microwave, and microemulsion methods. Among these, the high catalytic activity of AlOOH prepared by the microemulsion method is derived from its high specific surface area, more active surface OH groups, and multi-active adsorption sites. And nanomaterials with such excellent properties have not yet been fabricated on a SERS-based platform to improve the Raman-enhanced properties of Ag achieving high-sensitivity detection of probe molecules especially with affinity for OH groups. The precious metal Ag has long been known to serve as traps to capture electrons and holes generated by plasmon resonance, reducing electron–hole recombination and exhibiting high activity in photocatalytic processes. In this work, to demonstrate the SERS substrate activity of the AlOOH@Ag complex, it has been successfully applied to identify congo red (CR) molecules with high sensitivity, methyl blue (MB) and methyl orange (MO), enabling trace-level detection with enhanced performance much stronger than Ag substrate. [ABSTRACT FROM AUTHOR]

Various surface-enhanced Raman scattering (SERS) biosensors offer powerful tools for the ultrasensitive detection of circulating tumor cells (CTCs) and tumor diagnosis. Despite their efficacy, the swift and precise preparation of SERS plasmonic nanostructures poses an ongoing challenge. In this study, we introduce DNA-assisted plasmonic nanostructures capable of producing dual signals and facilitating DNA Walker signal amplification, resulting in the development of a SERS/Fluorescent (FL) dual-mode cytosensor for CTCs detection. Firstly, Au@Ag nanoparticle multimers (Au@AgNMs) featuring interparticle nano-gaps were synthesized through DNA self-assembly and in-situ deposition, which provided plasmonic nanostructures. Hence, the nano-gap distance among Au@AgNMs was meticulously regulated after optimization to achieve both SERS enhancement and fluorescence quenching. Subsequently, the aptamer (Apt) of MUC1 recognized CTCs specifically for strand displacement reaction (SDR) and further triggered the DNA Walker reaction for signal amplification. The limit of detection (LOD) of proposed cytosensor can be obtained as low as 5 cells/mL in SERS mode and 21 cells/mL in FL mode. Hence, SERS mode confers highly precise information, while FL mode allow for rapid quantitative analysis. This dual-mode cytosensor based on plasmonic nanostructures facilitates the early detection and precise treatment of cancer or infectious diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Photocatalysis is a cost-effective approach to producing renewable energy. A thorough comprehension of carrier separation at the micronano level is crucial for enhancing the photochemical conversion capabilities of photocatalysts. However, the heterogeneity of photocatalyst nanoparticles and complex charge migration processes limit the profound understanding of photocatalytic reaction mechanisms. By establishing the precise interrelationship between microscopic properties and photophysical behaviors of photocatalysts, single-particle fluorescence spectroscopy can elucidate the carrier separation and catalytic mechanism of the photocatalysts in situ, which provides perspectives for improving the photocatalytic efficiency. This Review primarily focuses on the basic principles and advantages of single-particle fluorescence spectroscopy and its progress in the study of plasmonic and semiconductor photocatalysis, especially emphasizing its importance in understanding the charge separation and photocatalytic reaction mechanism, which offers scientific guidance for designing efficient photocatalytic systems. Finally, we summarize and forecast the future development prospects of single-particle fluorescence spectroscopy technology, especially the insights into its technological upgrading.

Femtosecond (fs) laser pulses drive matter into a highly nonequilibrium state, allowing precise sculpturing of irradiated surface sites with sophisticated nanomorphologies. Here, we used fs-laser patterning to create diverse plasmonic morphologies on the top Au layer of the metal-insulator-metal sandwich. Mutual action of laser-driven thermomechanical effects and ultrafast solid-to-liquid transition allows control of the morphology resulting in pronounced surface reflectivity modulation, i.e., in a structural color effect. This enables template-free high-resolution color printing at a superior lateral resolution up to 50000 dots per inch and facile tunability of the color tone and saturation. Moreover, precise control over the orientation of the printed nanostructures within subwavelength lattices allows modulation of their local plasmonic response encrypting the optical information within the colorful images. The hidden information can be unveiled using a facile cross-polarized optical visualization scheme, rendering the proposed method with extra modalities combining high resolution information encryption, coloring, and security labeling.

The development of nanostructured plasmonic biosensors has been widely widespread in the last years, motivated by the potential benefits they can offer in integration, miniaturization, multiplexing opportunities, and enhanced performance label-free biodetection in a wide field of applications. Between them, engineering tissues represent a novel, challenging, and prolific application field for nanostructured plasmonic biosensors considering the previously described benefits and the low levels of secreted biomarkers (≈pM–nM) to detect. Here, we present an integrated plasmonic nanocrystals-based biosensor using high throughput nanostructured polycarbonate substrates. Metallic film thickness and incident angle of light for reflectance measurements were optimized to enhance the detection of antibody–antigen biorecognition events using numerical simulations. We achieved an enhancement in biodetection up to 3× as the incident angle of light decreases, which can be related to shorter evanescent decay lengths. We achieved a high reproducibility between channels with a coefficient of variation below 2% in bulk refractive index measurements, demonstrating a high potential for multiplexed sensing. Finally, biosensing potential was demonstrated by the direct and label-free detection of interleukin-6 biomarker in undiluted cell culture media supernatants from bioengineered 3D skeletal muscle tissues stimulated with different concentrations of endotoxins achieving a limit of detection (LOD) of ≈ 0.03 ng/mL (1.4 pM).

Shaping the emission pattern of second harmonic (SH) generation from plasmonic nanoparticles is important for practical applications in nonlinear nanophotonics but is rendered challenging by the complex second-order nonlinear-optical processes. Here, we theoretically and experimentally demonstrate that a pair of V- and Y-shaped gold nanoparticles directs the SH emission perpendicularly to an incident light direction. Owing to spatial overlap of two orthogonal plasmonic dipole modes at the fundamental and SH wavelengths of the individual particles, surface SH polarizations induced by the fundamental field is efficiently near-field coupled to the SH plasmon mode, resulting in dipolar SH emission from the individual particles. Moreover, the phase of this emission can be tuned simply by altering the part of the Y-particle shape, which changes the SH plasmon resonance while keeping the fundamental resonance. Our approach is a promising platform for engineering not only directional nonlinear nanoantennas but also nonlinear metamaterials.