Nanoantenna effect of surface-enhanced Raman scattering: managing light with plasmons at the nanometer scale

Abstract

Manipulating light on the nanometer scale is a challenging topic not only from a fundamental point of view, but also for applications aiming toward the design of miniature optical devices. Nanoplasmonics is a rapidly emerging branch of photonics, which offers variable means to manipulate light using surface plasmon excitations on metal nanostructures. As a spectroscopic phenomenon discovered nearly 40 years ago, surface-enhanced Raman scattering (SERS) has been an active topic of fundamental and applied researches. The dominating electromagnetic enhancement in SERS is caused by surface plasmon resonances. This is a typical example of manipulating light intensity with plasmons. Here, we will review the recent SERS studies related to nanoantenna effects on different metal nanostructures based on electromagnetic enhancement. Three aspects will be the focus in this paper: (1) the coupled nanostructures which act as receiving and emitting antenna that can generate enormous SERS enhancement ~E4 even enough for single molecule SERS. (2) The polarization of SERS at the single molecule limit, including the linear and circular polarizations can be manipulated using designed asymmetric antennas. Such an effect can make the traditional 1/2 and 1/4 wave plates miniaturized to the nanometer scale. (3) Combining nanoantenna and waveguiding effects, remote excitation of SERS can be realized, which may open a new area of single molecule SERS on nanophotonic circuits.

Investigation of simultaneously existed Raman scattering enhancement and inhibiting fluorescence using surface modified gold nanostars as SERS probes

“…Meanwhile, it is clearly seen that the GNS4 SERS probes with the longest tip displayed the strongest SERS signal, owing to the well-known hot spots effect 34 . For electromagnetic enhancement of SERS, the enhancement factor is proportional to the fourth power of the localized light intensity confined on the surfaces of metal nanostructures 35 . It has been verified that a single hot spot induced electromagnetic enhancement factor can reach as high as 10 9 , which is 3 to 4 orders of magnitude higher than that of an isolated metal nanoparticle.…”

Plasmonic refractive index sensing using strongly coupled metal nanoantennas: nonlocal limitations

“…Surface plasmons (SP) is the collective electromagnetic (EM) excitation of conduction electrons at metal-dielectric boundary, which can induce the confinement and enhancement of electric field near the surface of noble metallic nanostructures 1 . Local SP have been exploited to manipulate light-related phenomena at the nanoscale 2 , 3 , e.g. near-field enhancement (or “hot spot” distribution) 4 – 6 , emission polarization 7 – 10 , scattering direction 11 , optical force 12 , 13 , spin-orbit interaction 14 , and charge transfer 15 .…”

Advances in surface-enhanced vibrational spectroscopy at electrochemical interfaces

“…SERS is well established and has been the focus of several reviews [10][11][12][13][14][15][16][17][18][19][20]. The origin of the SERS enhancement effect has been the subject of some debate, although it is generally accepted that the primary mechanism of enhancement is amplification of the local electric field due to the resonant excitation of localised surface plasmons in the metal by the incident light, as well as non-resonant lightning rod effects associated with concentrated field lines at sharp surface features [21,22].…”