Symmetry Breaking in Gold Nanocylinder Grating: Influence on Plasmonic Properties and on Surface Enhanced Raman Scattering Performances

In this article, we study the influence of the symmetry breaking in nanocylinder gratings on the plasmonic properties and its impact on surface enhanced Raman scattering (SERS) performances. We modify the symmetry by changing the grating period in one direction from a square grating to rectangular grating that induces a modification of the symmetry group from C4v to C2v. We then observe a redshift and a narrowing of the plasmon resonance when the symmetry is reduced due to a coupling of the plasmon with a diffraction order of the grating. Remarkably, we demonstrate that such a coupling occurs whatever the polarization direction. We also demonstrate that the SERS efficiency of such plasmonic substrates is higher for the grating with a reduced symmetry due to a reduced width (full width half maximum) and a higher quality factor of the surface plasmon resonance.

Automated summary

In this article, the influence of symmetry breaking in nanocylinder gratings on plasmonic properties and surface enhanced Raman scattering (SERS) performances is studied. By changing the grating period and reducing the symmetry, a redshift and narrowing of plasmon resonance are observed, and the coupling between plasmons and diffraction order is found to occur regardless of polarization direction. It is also demonstrated that grating with reduced symmetry has higher SERS efficiency due to decreased width and increased quality factor of surface plasmon resonance.