Etienne Brasselet (Laboratoire Ondes et Matière d’Aquitaine): When chirality adds value to liquid crystal spin-orbit optics

Liquid crystals endowed with helical order are attracting interest since the early days of liquid crystals sciences. One of the reasons for it are the colorful manifestations that result from their chiral supramolecular structures, whenever the helical pitch value matches that of the wavelength of light. Physically, this is associated with the concept of photonic bandgap, which happens to depend on the polarization state of light for chiral anisotropic media such as cholesterics. Here we will discuss how polarization-dependent photonic bandgap finds interest in optics and photonics beyond colorful patterns, which is especially the case whenever the spatial degrees of freedom couple to the polarization state of light via the optical spin-orbit interaction.