Plasmonic oligomers in cylindrical vector light beams

Hentschel, Mario; Dorfmüller, Jens; Gießen, Harald; Jäger, Sebastian; Kern, Andreas; Braun, Kai; Zhang, Dai; Meixner, Alfred J.

doi:10.3762/bjnano.4.6

Cited by 16 publications

(19 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…or through the nanofabrication of assemblies of discs, squares, and bars using electron-beam lithography. 16,33,39,40 They typically extend over several 100 nm and sample the distribution of phase and polarization for visible light. 15,17,20,41 Structured light excites dipole-forbidden plasmons as shown for cylindrical vector beams 16,18 and light with orbital angular momentum.…”

Section: Introductionmentioning

confidence: 99%

Selection Rules for Structured Light in Nanooligomers and Other Nanosystems

2020

View full text Add to dashboard Cite

Structured light are custom light fields where the phase, polarization, and intensity vary with position. It has been used for nanotweezers, nanoscale imaging, and quantum information technology, but its role in exciting optical transitions in materials has been little examined so far. Here we use group theory to derive the optical selection rules for nanosystems that get excited by structured light. If the size of the nanostructure is comparable to the light wavelength, it will sample the full beam profile during excitation with profound consequences on optical excitations. Using nanooligomers as model nanosystems, we show that structured light excites optical transitions that are forbidden for linearly polarized or unpolarized light. Such dipole forbidden modes have longer lifetimes and narrower resonances than dipole allowed transitions. We derive symmetry-adapted eigenmodes for nanooligomers containing up to six monomers. Our study includes tables with selection rules for cylindrical vector beams, for beams with orbital angular momentum, and for field retardation along the propagation direction. We discuss multi-photon processes of nonlinear optics in addition to one-photon absorption. Structured light will unlock a broad range of excitations in nanooligomers and other nanostructures that are currently inaccessible to optical studies.

show abstract

Section: Introductionmentioning

confidence: 99%

Selection Rules for Structured Light in Nanooligomers and Other Nanosystems

2020

View full text Add to dashboard Cite

show abstract

“…As can be seen in Figure 1C, while the E z 2 component dominates the electric field intensity in the focus of a radially polarized beam, an exclusive E x,y 2 field intensity is present in the focus of an azimuthally polarized beam. These distinctly different electric field distributions allow the determination of the orientation of a dipole moment [32,33] or the selective excitation of a certain plasmonic mode [34]. Applying higher order laser modes in TERS has been proven advantageous.…”

Section: Parabolic-mirror-assisted Optical Microscopymentioning

confidence: 99%

Charge transfer and electromagnetic enhancement processes revealed in the SERS and TERS of a CoPc thin film

et al. 2019

Self Cite

View full text Add to dashboard Cite

Phthalocyanines are frequently used as probing molecules in the field of single-molecule surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS). In this work, we systematically compare the SERS and TERS spectra from a thin cobalt phthalocyanine (CoPc) film that is deposited on a Au film. The contributions from electromagnetic (EM), resonance, and charge-transfer enhancements are discussed. Radially and azimuthally polarized vector beams are used to investigate the influences of molecular orientation and the localized surface plasmon resonance (SPR). Furthermore, two different excitation wavelengths (636 and 532 nm) are used to study the resonant excitation effect as well as the involvement of the charge-transfer processes between CoPc and the Au substrate. It is shown that the Raman peaks of CoPc are mostly enhanced by 636 nm excitation through a combination of resonant excitation, high EM enhancement, and chemical enhancement via charge transfer from the metal to the molecule. At 532 nm excitation, however, the SERS and TERS spectra are dominated by photoluminescence, which originates from a photo-induced charge-transfer process from the optically excited molecule to the metal. The contributions of the different enhancement mechanisms explain the optical contrasts seen in the TERS images of Au nanodisks covered by the CoPc film. The insight achieved in this work will help to understand the optical contrast in sub- or single-molecule TERS imaging and apply SERS or TERS in the field of photocatalysis.

show abstract

“…Up to now, the excitation of plasmon eigenmodes by structured light was examined on a case by case basis using numerical simulations of the absorption and scattering spectra. Structured light beams were used for exciting dark and bright plasmons with a complex distribution of surface charge density in nanooligomers [2,19,20,21,22], gold tetramers surrounded by a gold nanodisk array [23], coupled nano antennas [24], concentric spirals [25], and a plasmonic coaxial nanoring [26]. The case-by-case approach, however, is inherently limited.…”

Section: Introductionmentioning

confidence: 99%

Selective excitation of localized surface plasmons by structured light

Litvin¹,

Mueller²,

Reich³

2020

Opt. Express

View full text Add to dashboard Cite

We investigated the selective excitation of localized surface plasmons by structured light. We derive selection rules using group theory and propose a fitting integral to quantify the contribution of the eigenmodes to the absorption spectra. Based on the result we investigate three nano oligomers of different symmetry (trimer, quadrumer, and hexamer) in detail using finitedifference time-domain simulations. We show that by controlling the incident light polarization and phase pattern we are able to control the absorption and scattering spectra. Additionally, we demonstrate that the fitting between the incident light and the oligomer modes may favor a number of modes to oscillate. Dark modes produce strong changes in the absorption spectrum and bright modes in the scattering spectrum. The experimental precision (axial shift error) may be on the same order as the oligomer diameter making the orbital angular momentum selection rules robust enough for experimental observation.

show abstract

Plasmonic oligomers in cylindrical vector light beams

Cited by 16 publications

References 36 publications

Selection Rules for Structured Light in Nanooligomers and Other Nanosystems

Selection Rules for Structured Light in Nanooligomers and Other Nanosystems

Charge transfer and electromagnetic enhancement processes revealed in the SERS and TERS of a CoPc thin film

Selective excitation of localized surface plasmons by structured light

Contact Info

Product

Resources

About