After one year, we have developed various chiral liquid crystal mixtures whose internal chiral properties are optically addressable. Structural and optical characterization has been performed. The response to optical stimuli has been studied and has revealed the appearance of structures involving various topologies and symmetries. The dynamical response of the system has been found to exhibit a robust and unexpected behavior, which has been fully characterized: it corresponds to the original realization of a continuously rotating soft engine driven by light under fixed irradiation conditions. In practice, we experimentally studied the conditions of formation of various kinds of localized topological patterns in chiral nematic films with perpendicular boundary conditions, which behave as elastic quasi-particles sustained by light. We unraveled their stability depending on the composition of liquid crystal mixture (nature and relative concentrations of passive and/or active chiral dopants added to a passive nonchiral nematic liquid crystal host) and the irradiation conditions (beam size, beam power, polarization state of light, duration of excitation, etc.). We also revealed the emergence of asymmetric and dynamical patterns encoded at the molecular level. From an interpretation point of view, we proposed a simplified physico-chemical model for the discovered continuous, regular and unidirectional rotation of a localized chiral liquid crystal structure, which is based on the interplay between the twist of the supramolecular structure and the diffusion of the chiral molecular nano-motors through an inhomogeneous and chiral fluidic environment. We also demonstrated that the work produced by the revolving supramolecular structure can be harnessed into the rotation of a cargo.
