Near infrared light amplification in Gold diffused Silicon-on-Insulator waveguides

Spaser and optical amplification conditions in gold-coated active nanoparticles

Due to their many potential applications, there is an increasing interest in studying hybrid systems composed of optically active media and plasmonic metamaterials. In this work we focus on a particular system which consists of an optically active silica core covered by a gold shell. We find that the spaser (surface plasmon amplification by stimulated emission of radiation) conditions can be found at the poles of the scattering cross section of the system, a result that remains valid beyond the geometry studied. We explored a wide range of parameters that cover most of the usual experimental c…

使用纳米颗粒杂交测定法进行特异性核酸检测

Specific Nucleic Acid Detection Using a Nanoparticle Hybridization Assay

本研究开发盐老化偶联引物的金纳米颗粒杂交聚集测定，无需信号放大即可特异性识别SARS-CoV-2的94 bp DNA靶序列，并通过等离子体位移、电泳和扩散系数验证其可行性。

The Prevailing Role of Hotspots in Plasmon-Enhanced Sum-Frequency Generation Spectroscopy

The plasmonic amplification of non-linear vibrational sum frequency spectroscopy (SFG) at the surfaces of gold nanoparticles is systematically investigated by tuning the incident visible wavelength. The SFG spectra of dodecanethiol-coated gold nanoparticles chemically deposited on silicon are recorded for twenty visible wavelengths. The vibrational intensities of thiol methyl stretches extracted from the experimental measurements vary with the visible color of the SFG process and show amplification by coupling to plasmonics. Since the enhancement is maximal in the orange-red region rather than…

Light amplification by stimulated emission from an optically pumped molecular junction in a scanning tunneling microscope

Here, we introduce and experimentally demonstrate optical amplification and stimulated emission from a single optically pumped molecular tunneling junction of a scanning tunneling microscope. The gap between a sharp gold tip and a flat gold substrate covered with a self-assembled monolayer of 5-chloro-2-mercaptobenzothiazole molecules forms an extremely small optical gain medium. When electrons tunnel from the molecules highest occupied molecular orbital to the tip, holes are left behind. These can be repopulated by hot electrons induced by the laser-driven plasmon oscillation on the metal sur…

Optical detection of single non-absorbing molecules using the surface plasmon of a gold nanorod

Current optical detection schemes for single molecules require light absorption, either to produce fluorescence or direct absorption signals. This severely limits the range of molecules that can be detected, because most molecules are purely refractive. Metal nanoparticles or dielectric resonators detect non-absorbing molecules by a resonance shift in response to a local perturbation of the refractive index, but neither has reached single-protein sensitivity. The most sensitive plasmon sensors to date detect single molecules only when the plasmon shift is amplified by a highly polarizable labe…

Design Considerations of Gold Nanoantenna Dimers for Plasmomechanical Transduction

Internal optical forces emerging from plasmonic interactions in gold nanodisc, nanocube and nanobar dimers were studied by finite element method. A direct correlation between the electric-field enhancement and optical forces was found by observing largest magnitude of optical forces in nanocube dimers. Moreover, further amplification of optical forces was achieved by employing optical power of the excitation source. The strength of optical forces was observed to be governed by the magnitude of polarisation density on the nanoparticles, which can be varied by modifying the nanoparticle geometry…