Cholesteric solid spherical microparticles: chiral optomechanics and microphotonics

Abstract

This manuscript reviews the main results from the investigations performed on solid chiral micro-particles based on polymerized cholesteric droplets. The procedures of particles generation, the structural characterization, optomechanics and microphotonics investigations, are shown. The aim of this work is to give a picture of the innovation introduced by exploring the combination of chirality, self-organization and solid structure.

Light-induced rotations of chiral birefringent microparticles in optical tweezers

“…The self-organized internal configuration of the droplet strongly depends on the molecular anchoring at the interface and on its radius R 0 with respect to the nominal pitch p of the helical structures. In our case, R 0  ≅ 1 μm and p  ≅ 0.51 μm, and, thus, the low chirality regime can be considered283132 that is in agreement with a low reflectivity and a not negligible residual retardance.…”

Chirality-assisted lateral momentum transfer for bidirectional enantioselective separation

“…Finally, the value of particle reflectance R s depending on the light polarization, the particle size and the light wavelength can be expressed as 45,46…”

“…Due to the low absorption of the materials at the used wavelength, the value of the molecular circular dichroism is very small. However, at this wavelength, the circular dichroism stems from diffraction of light 46,53,54 . A Braggreflection phenomenon 46,53,54 occurs for circularly polarized light with the same handedness as the material/ particle chirality due to the supramolecular shell arrangement.…”

“…However, at this wavelength, the circular dichroism stems from diffraction of light 46,53,54 . A Braggreflection phenomenon 46,53,54 occurs for circularly polarized light with the same handedness as the material/ particle chirality due to the supramolecular shell arrangement. Such "structural dichroism" can be evaluated by the difference between the transmission coefficients of the two circular polarizations, D ¼ T þ ÀT À T þ þT Àl , where T +/− are the transmittances for left/right CP light 46,53,54 .…”

“…A Braggreflection phenomenon 46,53,54 occurs for circularly polarized light with the same handedness as the material/ particle chirality due to the supramolecular shell arrangement. Such "structural dichroism" can be evaluated by the difference between the transmission coefficients of the two circular polarizations, D ¼ T þ ÀT À T þ þT Àl , where T +/− are the transmittances for left/right CP light 46,53,54 . Accordingly, omnidirectional uniform reflectance occurs for particles with a radial configuration of the helical axes, as shown in Fig.…”