Thermally and Electrically Regulated Plasmonic Devices Based on VO-Covered Gold Nanoplate Arrays with SiO Interface Layer for Large Plasmon Shifts.

Integrating metal nanoparticles with vanadium dioxide (VO) is an effective means to realize active plasmonic regulation which has great application potential in optical devices that respond in real-time to external stimuli. However, the high temperature necessary for VO growth severely reshapes the metal nanoparticles, causing reduced refractive index (RI) sensitivity and degraded modulation performance. Herein, we construct a large-area dynamically tunable plasmonic system composed of a VO-covered array of hexagonal gold nanoplates (AuNPLs).

Flexible Multicavity SERS Substrate Based on Ag Nanoparticle-Decorated Aluminum Hydrous Oxide Nanoflake Array for Highly Sensitive Detection.

Flexible surface-enhanced Raman scattering (SERS) substrates are very promising to meet the needs for real-time and on-field detection in practical applications. However, high-performance flexible SERS substrates often suffer from complexity and high cost in fabrication, limiting their widespread applications. Herein, we developed a facile method to fabricate a flexible multicavity SERS substrate composed of a silver nanoparticle (AgNP)-decorated aluminum hydrous oxide nanoflake array (NFA) grown on a polydimethylsiloxane (PDMS) membrane.

Investigating exceptional points in dark-bright mode-coupled plasmonic systems.

Exceptional points (EPs) of non-Hermitian systems are gaining more and more attention due to their important applications in unidirectional transmitters, sensors, etc. However, theoretical studies on EPs of reflection, transmission, and absorption spectra are less available. In this paper, in the dark-bright mode-coupled plasmonic systems, the variations of EPs of reflection, transmission, and absorption spectra are numerically investigated using temporal coupled-mode theory, and an assumption is given using the representation transformation theory.

Quantitative Insights into a Plasmonic Ruler Equation from the Perspective of Enhanced Near Field.

The plasmonic shift of resonance wavelength induced by near-field coupling enables one to measure nanoscale distances optically. Empirically, the well-known ruler equation correlating plasmon shift with interparticle spacing was proposed. Though it has been widely used in analyzing simulation and experimental outcomes, little is known about the underlying physical mechanism of the characteristic exponential form of the plasmon ruler equation and the universal decay constant therein.

Efficient planar plasmonic directional launching of linearly polarized light in a catenary metasurface.

Efficient directional excitation of planar surface plasmon polaritons (SPPs) has important and wide applications in micro-nano photonic technology. Recently, by using the geometric phase and spin-orbit interaction, catenary structures have been applied to the directional control of SPPs and showed excellent performance. However, due to the need to use the chirality of the subwavelength catenary apertures, the previously studied systems were only suitable for circularly polarized light.

Effective plasmon coupling in conical cavities for sensitive surface enhanced Raman scattering with quantitative analysis ability.

Conical silver nanocavity arrays are fabricated by directly depositing Ag on porous alumina templates with V-shaped nanopores. By controlling the thickness of deposited Ag, complete and cracked cavity arrays are constructed respectively. The cracked cavity arrays with the cavity wall consisting of Ag nanoparticles are demonstrated to exhibit higher surface enhanced Raman scattering (SERS) activity than the complete one.

A porous Au-Ag hybrid nanoparticle array with broadband absorption and high-density hotspots for stable SERS analysis.

Constructing high-density hotspots is of crucial importance in surface enhanced Raman scattering (SERS). In this paper, we present a large-area and broadband porous Au-Ag hybrid nanoparticle array which was fabricated by an ultra-thin alumina mask (UTAM) technique incorporated with annealing and galvanic replacement techniques. Experimental results and numerical simulations demonstrated that the porous Au-Ag hybrid nanoparticle array possessed enormous hotspots for high sensitivity, uniformity, and stability in SERS analysis.

Fluorescence emission difference with surface plasmon-coupled emission applied in confocal microscopy.

We combined confocal surface plasmon coupled emission microscopy (C-SPCEM) together with fluorescence emission difference (FED) technique to pursuit super-resolution fluorescent image. Solid or hollow point spread function (PSF) for C-SPCEM is achieved with radially-polarized or circularly-polarized illumination. The reason why PSF can be manipulated by the polarization of illumination light is corroborated by the interaction of fluorescent emitter with vector focal field on the plasmonic substrate.

Free-standing Ag triangle arrays a configurable vertical gap for surface enhanced Raman spectroscopy.

Large-area ordered arrays with dense hotspots are highly desirable substrates for surface enhanced Raman scattering (SERS). In this paper, we present a quasi-3D SERS substrate of free-standing Ag triangle arrays (FATA) which was fabricated by nanosphere lithography incorporated with photolithography and Ag covering. A significant SERS effect arises from a strongly enhanced local electric field within the tiny gaps between the suspended Ag triangle and the Ag baseplate.

Large-area, reproducible and sensitive plasmonic MIM substrates for surface-enhanced Raman scattering.

Vertically coupled plasmonic structure is of great interest for surface-enhanced Raman scattering (SERS). In this paper, a large-area reproducible SERS substrate is fabricated and demonstrated by a vertically coupled structure composed of Ag triangle arrays on Ag films separated by a nanometric dielectric layer. This metal-insulator-metal (MIM) nanostructure has broadband resonance covering both the laser excitation and Stokes frequencies.

Far-field radially polarized focal spot from plasmonic spiral structure combined with central aperture antenna.

Manipulation of a vector micro-beam with an optical antenna has significant potentials for nano-optical technology applications including bio-optics, optical fabrication, and quantum information processing. We have designed and demonstrated a central aperture antenna within an Archimedean spiral that extracts the bonding plasmonic field from a surface to produce a new vector focal spot in far-field. The properties of this vector focal field are revealed by confocal microscopy and theoretical simulations.

Raman scattering enhanced within the plasmonic gap between an isolated Ag triangular nanoplate and Ag film.

Enhanced electromagnetic field in the tiny gaps between metallic nanostructures holds great promise in optical applications. Herein, we report novel out-of-plane nanogaps composed of micrometer-sized Ag triangular nanoplates (AgTN) on Ag films. Notably, the new coupled plasmonic structure can dramatically enhance the surface-enhanced Raman scattering (SERS) by visible laser excitation, although the micrometer-sized AgTN has localized plasmon resonance at infrared wavelength.