We designed and fabricated an array of metallic nano-aperture on a gold film to enhance the detection of immunoglobulin G (IgG) protein in the liquid environment. The plasmonic nanostructure is designed to exhibit a resonance at 762 nm. The field enhancement improved the sensitivity of the system, enabling the detection of IgG protein at low concentrations, i.e. 4 ng/ml. Raman spectroscopy was employed to record the protein’s spectral signatures at multiple locations across the plasmonic nanostructure under laser excitation at 530 nm, revealing an enhancement in the Raman signal. This work paves the way for developing plasmonic nanostructures suitable for large-scale applications, with particular potential in diagnostics and environmental studies.

In this research rhodium nanoparticles (RhNPs) were synthesized and used for studying the fluorescence of aromatic amino acids (tryptophan (Trp) and tyrosine (Tyr)). Stern-Volmer plots were constructed and the corresponding quenching constants were calculated. It was determined that with increasing concentration of RhNPs, the fluorescence intensity of aromatic amino acids decreases as a result of different types of quenching.

To effectively utilize photon spin is crucial for developing integrated nano-circuits on a chip. However, the spin-orbit interaction of light is typically very weak at nanoscale due to the diffraction limit. While the unidirectional transmission capability can be highly enhanced on subwavelength scales with suitable architectures. Here we propose a dielectric-loaded plasmonic nanocircuit with a spin sorting coupler to directionally couple and guide plasmonic waves through two-branched waveguides. Optimized results reveal that the waveguide modes excited by circularly polarized light with different spin states can be selectively coupled to one of the two targeted branch waveguides, with a calculated unidirectional coupling efficiency as high as 0.95. In addition, a central symmetric structure is implemented, which demonstrates great potential in designing complex interconnect nanocircuits. The illustrated approach is believed to open the way for the development of monolithic plasmonic nanocircuits with flexible freedoms.

Plasmonic Bessel-like beams have potential applications in nanophotonics, particularly in photonic circuits, micro manipulations, and near field-optical trapping. However, the existing methods all require an axicon-shaped or X-shaped slit array, which not only occupies a large space, but also affects the beam coverage range. In this paper, one compact strategy using two straight columns of nanoslits is proposed to generate a Bessel beam on the two sides. Bessel beams of different orders and tilted angles can be simply achieved using double slit arrays.

Laser-induced periodic surface structures (LIPSS) offer a simple, single-step technique for creating periodic patterns on solids in an ambient air. Combined with metals like gold or silver, LIPSS enhances grating-assisted refractive index (RI) sensors using surface plasmon resonance (SPR). This study analyzes an SPR sensor in the Kretschmann configuration with a periodically modulated silver layer. The modulation is created by LIPSS formed on a titanium-coated glass prism using femtosecond laser pulses, followed by a silver coating. Reflection spectra for wavelengths λ = 600-1700 nm were calculated for various angles of incidence and RI values (1.33- 1.4). Unlike a flat sensor with a single resonance, the LIPSS-based sensor shows multiple resonances (λ = 1000-1700 nm) due to modes on inner and outer interfaces. LIPSS reduces resonance spectral width by an order of magnitude, but also reduces sensitivity similarly, weakly affecting the Figure of Merit. The LIPSS-assisted sensor was also tested experimentally.