The beginnings of plasmomechanics： towards plasmonic strain sensors

This article exposes the beginnings of a new field which could be named as ＂plasmomechanics＂. Plasmomechanics comes from the convergence between mechanics and plasmonics. Here we discuss a relatively recent topic whose technolo- gical aim is the development of plasmonic strain sensors, The idea is based on the ability to deduce Au nanoparticles （NPs） distance distributions from polarized optical extinction spectroscopy which could thus give access to material strains. Variations of interparticle distances distributions can indeed lead to variations of plasmonic coupling and thus to material color change as shown here experimentally and numerically for random Au NP assemblies deposited onto elastomer films,

Directional radiation enhancement of nanowire quantum dots based on line-array plasmonic antenna coupling

The integration of a single III-V semiconductor quantum dot with a plasmonic nanoantenna as a means toward efficient single-photon sources(SPEs)is limited due to its weak,wide-angle emission,and low emission rate.These limitations can be overcome by designing a unique linear array of plasmonic antenna structures coupled to nanowire-based quantum dot(NWQD)emitters.A linear array of a coupled device composed of multiple plasmonic antennas at an optimum distance from the quantum dot emitter can be designed to enhance the directionality and the spontaneous emission rate of an integrated single-photon emitter.Finite element modeling has been used to design these compact structures with high quantum efficiencies and directionality of single-photon emission while retaining the advantages of NWQDs.The Purcell enhancement factor of these structures approaches 66.1 and 145.8,respectively.Compared to a single NWQD of the same diameter,the fluorescence was enhanced by 1054 and 2916times.The predicted collection efficiencies approach 85%(numerical aperture,NA=0.5)and 80%(NA=0.5),respectively.Unlike single-photon emitters based on bulky conventional optics,this is a unique nanophotonic single-emission photon source based on a line-array configuration that uses a surface plasmon-enhanced design with minimum dissipation.The designs presented in this work will facilitate the development of SPEs with potential integration with semiconductor optoelectronics.

Active spatial control of photothermal heating and thermo-actuated convective flow by engineering a plasmonic metasurface with heterodimer lattices

Thermo-plasmonics, using plasmonic structures as heat sources, has been widely used in biomedical and microfluidic applications. However, a metasurface with single-element unit cells, considered as the sole heat source in a unit cell, functions at a fixed wavelength and has limited control over the thermo-plasmonically induced hydrodynamic effects. Plasmonic metasurfaces with metal disk heterodimer lattices can be viewed to possess two heat sources within a unit cell and are therefore designed to photo-actively control thermal distributions and fluid dynamics at the nanoscale. The locations of heat sources can be switched, and the direction of the convective flow in the central region of the unit cell can be reversed by shifting the wavelength of the excitation source without any change in the excitation direction or physical actuation of the structural elements. The temperature and velocity of a fluid are spatiotemporally controlled by the wavelength selectivity and polarization sensitivity of the plasmonic metasurface. Additionally, we investigate the effects of geometric parameters on the surface lattice resonances and their impact on the temperature and fluid velocity of the optofluidic system. Our results demonstrate excellent optical control of these plasmonic metasurface heating and thermal convection performances to design flexible platforms for microfluidics.