Explore the vast range of titles available.

Surface plasmonic sensors have been widely used in biology, chemistry, and environment monitoring. These sensors exhibit extraordinary sensitivity based on surface plasmon resonance (SPR) or localized surface plasmon resonance (LSPR) effects, and they have found commercial applications. In this review, we present recent progress in the field of surface plasmonic sensors, mainly in the configurations of planar metastructures and optical-fiber waveguides. In the metastructure platform, the optical sensors based on LSPR, hyperbolic dispersion, Fano resonance, and two-dimensional (2D) materials integration are introduced. The optical-fiber sensors integrated with LSPR/SPR structures and 2D materials are summarized. We also introduce the recent advances in quantum plasmonic sensing beyond the classical shot noise limit. The challenges and opportunities in this field are discussed.

The properties of propagating surface plasmon polaritons (SPPs) along one-dimensional metal structures have been investigated for more than 10 years and are now well understood. Because of the high confinement of electromagnetic energy, propagating SPPs have been considered to represent one of the best potential ways to construct next-generation circuits that use light to overcome the speed limit of electronics. Many basic plasmonic components have already been developed. In this review, researches on plasmonic waveguides are reviewed from the perspective of plasmonic circuits. Several circuit components are constructed to demonstrate the basic function of an optical digital circuit. In the end of this review, a prototype for an SPP-based nanochip is proposed, and the problems associated with building such plasmonic circuits are discussed. A plasmonic chip that can be practically applied is expected to become available in the near future. Plasmonics: nanophotonic circuitry The prospects for creating sophisticated nanophotonic circuits by harnessing the opportunities provided by plasmonics are exciting. Yurui Fang and Mengtao Sun from the Beijing National Laboratory for Condensed Matter Physics review recent progress in the development of various components and devices for generating, manipulating and detecting surface plasmon polaritons — tightly confined waves that can be excited by light at the interface between a metal and a dielectric. Their small size offers opportunities for constructing photonic devices that are smaller than the wavelength of light, a major barrier to the miniaturization of optical integrated circuits. Fang and Sun describe how nanoscale waveguides, multiplexers, lasers, high-speed modulators, logic gates and detectors for surface plasmon polaritons are all coming to fruition. They also consider the future prospects of this technology.

We propose and demonstrate one-dimensional (1-D) TiO dielectric grating structures that couple 793-nm wavelength light and two-dimensional (2-D) surface plasmon polaritons (SPPs) into guided 1-D SPPs supported by dielectric-loaded plasmonic waveguides. The 1-D grating structure consists of a central TiO stripe with a periodic array of TiO teeth attached to the stripe. Finite-difference time-domain (FDTD) simulations reveal that the electromagnetic boundary conditions created by the teeth bend the electric field and induce charge oscillations under the grating, enabling excitation of SPPs. The same mechanism supports the routing of 2-D SPP. In the simulation the symmetric gratings achieve a maximum coupling efficiency of 19.1 % at an optimized grating period of Λ = 600 nm, and 1.7 % for asymmetric gratings. Both types exhibit strong polarization selectivity: symmetric gratings couple only under TM excitation, whereas asymmetric gratings respond under TE excitation. Experimental confirms these behaviors, yielding a coupling efficiency of ∼13 % for optimized symmetric gratings. The structures also function as SPP routers. Asymmetric gratings route incoming 2-D SPPs into 1-D TiO waveguides with a simulated routing efficiency of 5.7 %, compared to 4.0 % for symmetric designs. The devices offer a ∼14 nm bandwidth around 793 nm and a small footprint of 18.7 μm , resulting in a figure of merit (efficiency/area) of 0.71 % μm , the highest among reported devices designed to couple free-space light directly into 1-D SPP waveguides. These results demonstrate that 1-D TiO gratings offer a compact and multifunctional platform for efficient coupling and routing of SPPs in integrated plasmonic circuits.

We report on the detection and quantification of aqueous DNA by a fluorophore-induced plasmonic current (FIPC) sensing method. FIPC is a mechanism described by our group in the literature where a fluorophore in close proximity to a plasmonically active metal nanoparticle film (MNF) is able to couple with it, when in an excited state. This coupling produces enhanced fluorescent intensity from the fluorophore–MNF complex, and if conditions are met, a current is generated in the film that is intrinsically linked to the properties of the fluorophore in the complex. The magnitude of this induced current is related to the spectral properties of the film, the overlap between these film properties and those of the fluorophore, the spacing between the nanoparticles in the film, the excitation wavelength, and the polarization of the excitation source. Recent literature has shown that the FIPC system is ideal for aqueous ion sensing using turn-on fluorescent probes, and in this paper, we subsequently examine if it is possible to detect aqueous DNA also via a turn-on fluorescent probe, as well as other commercially available DNA detection strategies. We report the effects of DNA concentration, probe concentration, and probe characteristics on the development of an FIPC assay for the detection of non-specific DNA in aqueous solutions.

Plasmonic metal‐organic frameworks are composite nanoparticles comprising plasmonic metal nanoparticles (NPs) embedded within a metal‐organic framework (MOF) matrix. As a result, not only the functionalities of the individual components are retained, but synergistic effects additionally provide improved chemical and physical properties. Recent progress in plasmonic MOFs has demonstrated the potential for nanofabrication and various nanotechnology applications. Synthetic challenges toward plasmonic MOFs have been recently addressed, resulting in new opportunities toward practical applications, such as surface‐enhanced Raman scattering, therapy, and catalysis. The impact of key parameters (thermodynamic vs. kinetic) on the synthetic pathways of plasmonic MOFs is reviewed, while providing insight into related progress toward structure‐derived applications. Plasmonic metal‐organic frameworks hybrid nanocomposites feature improved chemical and physical properties, as compared with their individual components, due to synergistic performance. These materials show excellent opportunities toward practical applications, such as surface‐enhanced Raman scattering, therapy, and catalysis.

The extension of plasmonics to materials beyond the conventional noble metals opens up a novel and exciting regime after the inspiring discovery of characteristic localized surface plasmon resonances (LSPRs) in doped semiconductor nanocrystals originating from the collective oscillations of free holes in the valence band. We herein prepare colloidal monodisperse eccentric dual plasmonic noble metal-nonstoichiometric copper chalcogenide (Au@Cu 2− x Se) hybrid hetero-nanostructures with precisely controlled semiconductor shell size and two tunable LSPRs in both visible (VIS) and near-infrared (NIR) regions associated with Au and Cu 2− x Se, respectively. Through systematic evaluations of the photocatalytic performance of Au@Cu 2− x Se upon sole NIR and dual VIS + NIR simultaneous excitations, we are capable of unambiguously elucidating the role of plasmonic coupling between two dissimilar building blocks on the accelerated photocatalytic reactions with greater rate constants from both experimental and computational perspectives. The significantly enhanced strength of the electromagnetic field arising from efficient plasmonic coupling under the excitation of two LSPRs results in the superior activities of dual plasmonic Au@Cu 2− x Se in photocatalysis. The new physical and chemical insights gained from this work provide the keystone for the rational design and construction of high-quality dual- or even multi-plasmonic nano-systems with optimized properties for widespread applications ranging from photocatalysis to molecular spectroscopies.

Herein, a facile self‐assembly strategy for coassembling oleic acid‐coated iron oxide nanoparticles (OC‐IONPs) with oleylamine‐coated gold nanoparticles (OA‐AuNPs) to form colloidal magnetic–plasmonic nanoassemblies (MPNAs) is reported. The resultant MPNAs exhibit a typical core–shell heterostructure comprising aggregated OA‐AuNPs as a plasmonic core surrounded by an assembled magnetic shell of OC‐IONPs. Owing to the high loading of OA‐AuNPs and reasonable spatial distribution of OC‐IONPs, the resultant MPNAs exhibit highly retained magnetic–plasmonic activities simultaneously. Using the intrinsic dual functionality of MPNAs as a magnetic separator and a plasmonic signal transducer, it is demonstrated that the assembled MPNAs can achieve the simultaneous magnetic manipulation and optical detection on the lateral flow immunoassay platform after surface functionalization with recognition molecules. In conclusion, the core–shell‐heterostructured MPNAs can serve as a nanoanalytical platform for the separation and concentration of target compounds from complex biological samples using magnetic properties and simultaneous optical sensing using plasmonic properties. Herein, the facile synthesis of magnetic–plasmonic nanoassemblies (MPNAs) is reported, which exhibit a typical core–shell structure, wherein oleylamine‐coated gold nanoparticles (OA‐AuNPs) preferentially aggregate and form a plasmonic core and oleic acid‐coated iron oxide nanoparticles (OC‐IONPs) assemble a magnetic shell. The resultant MPNAs hold the highly retained magnetic–plasmonic activities for the separation and simultaneous optical sensing of target compounds in complex biological samples.

Plasmonic effect using a cross-hair can convey strongly localized surface plasmon modes among the separated composite nanostructures. Compared to its counterpart without the cross-hair, this characteristic has the remarkable merit of enhancing absorptance at resonance and can make the structure carry out a dual-band plasmonic perfect absorber (PPA). In this paper, we propose and design a novel dual-band PPA with a gathering of four metal-shell nanorods using a cross-hair operating at visible and near-infrared regions. Two absorptance peaks at 1050 nm and 750 nm with maximal absorptance of 99.59% and 99.89% for modes 1 and 2, respectively, are detected. High sensitivity of 1200 nm refractive unit (1/RIU), figure of merit of 26.67 and Q factor of 23.33 are acquired, which are very remarkable compared with the other PPAs. In addition, the absorptance in mode 1 is about nine times compared to its counterpart without the cross-hair. The proposed structure gives a novel inspiration for the design of a tunable dual-band PPA, which can be exploited for plasmonic sensor and other nanophotonic devices.

This review aims to summarize the recent advances and progress of plasmonic biosensors based on patterned plasmonic nanostructure arrays that are integrated with microfluidic chips for various biomedical detection applications. The plasmonic biosensors have made rapid progress in miniaturization sensors with greatly enhanced performance through the continuous advances in plasmon resonance techniques such as surface plasmon resonance (SPR) and localized SPR (LSPR)-based refractive index sensing, SPR imaging (SPRi), and surface-enhanced Raman scattering (SERS). Meanwhile, microfluidic integration promotes multiplexing opportunities for the plasmonic biosensors in the simultaneous detection of multiple analytes. Particularly, different types of microfluidic-integrated plasmonic biosensor systems based on versatile patterned plasmonic nanostructured arrays were reviewed comprehensively, including their methods and relevant typical works. The microfluidics-based plasmonic biosensors provide a high-throughput platform for the biochemical molecular analysis with the advantages such as ultra-high sensitivity, label-free, and real time performance; thus, they continue to benefit the existing and emerging applications of biomedical studies, chemical analyses, and point-of-care diagnostics.

Plasmonic nanostructures can concentrate light and enhance light-matter interactions in the subwavelength domain, which is useful for photodetection, light emission, optical biosensing, and spectroscopy. However, conventional plasmonic devices and systems are typically optimized for the operation in a single wavelength band and thus are not suitable for multiband nanophotonics applications that either prefer nanoplasmonic enhancement of multiphoton processes in a quantum system at multiple resonant wavelengths or require wavelength-multiplexed operations at nanoscale. To overcome the limitations of “single-resonant plasmonics,” we need to develop the strategies to achieve “multiresonant plasmonics” for nanoplasmonic enhancement of light-matter interactions at the same locations in multiple wavelength bands. In this review, we summarize the recent advances in the study of the multiresonant plasmonic systems with spatial mode overlap. In particular, we explain and emphasize the method of “plasmonic mode hybridization” as a general strategy to design and build multiresonant plasmonic systems with spatial mode overlap. By closely assembling multiple plasmonic building blocks into a composite plasmonic system, multiple nonorthogonal elementary plasmonic modes with spectral and spatial mode overlap can strongly couple with each other to form multiple spatially overlapping new hybridized modes at different resonant energies. Multiresonant plasmonic systems can be generally categorized into three types according to the localization characteristics of elementary modes before mode hybridization, and can be based on the optical coupling between: (1) two or more localized modes, (2) localized and delocalized modes, and (3) two or more delocalized modes. Finally, this review provides a discussion about how multiresonant plasmonics with spatial mode overlap can play a unique and significant role in some current and potential applications, such as (1) multiphoton nonlinear optical and upconversion luminescence nanodevices by enabling a simultaneous enhancement of optical excitation and radiation processes at multiple different wavelengths and (2) multiband multimodal optical nanodevices by achieving wavelength multiplexed optical multimodalities at a nanoscale footprint.