Towards chiral acoustoplasmonics

Abstract

The possibility of creating and manipulating nanostructured materials encouraged the exploration of new strategies to control electromagnetic properties. Among the most intriguing nanostructures are those that respond differently to helical polarization, i.e., exhibit chirality. Here, we present a simple structure based on crossed elongated bars where light-handedness defines the dominating cross-section absorption or scattering, with a 200 % difference from its counterpart (scattering or absorption). The proposed chiral system opens the way to enhanced coherent phonon excitation and detection. We theoretically propose a simple coherent phonon generation (time-resolved Brillouin scattering) experiment using circularly polarized light. In the reported structures, the generation of acoustic phonons is optimized by maximizing the absorption, while the detection is enhanced at the same wavelength and different helicity by engineering the scattering properties. The presented results constitute one of the first steps towards harvesting chirality effects in the design and optimization of efficient and versatile acoustoplasmonic transducers.

Enhanced efficiency of coherent acoustic phonon generation and detection using elliptical micropillars

“…1,4,[6][7][8][9][10] Excitation and detection at different wavelengths is another method to improve the phonon signal that has been applied in plasmonic resonators and quantum dot layer systems. [11][12][13] However, most of these approaches are based on altering experimental conditions. In this work, we use micropillars with elliptical cross-sections to enhance the phonon amplitude based on a standard pumpprobe scheme with one single wavelength and normal incidence on the sample.…”