International audienceThe lack of mirror symmetry, chirality, plays a fundamental role in physics, chemistry and life sciences. The passive separation of entities that only differ by their handedness without need of a chiral material environment remains a challenging task with attractive scientific and industrial benefits. To date, only a few experimental attempts have been reported and remained limited down to the micron scale, most of them relying on hydrodynamical forces associated with the chiral shape of the micro-objects to be sorted. Here we experimentally demonstrate that material chirality can be passively sorted in a fluidic environment by chiral light owing to spin-dependent optical forces without chiral morphology prerequisite. This brings a new twist to the state-of-the-art optofluidic toolbox and the development of a novel kind of passive integrated optofluidic sorters able to deal with molecular scale entities is envisioned

The rule of thumb of tailored optical forces consists in the control of linear momentum exchange between light and matter. This may be done by appropriate selection of the interaction geometry, optical modes or environmental characteristics. Here we reveal that the interplay of the helicity of light and the chirality of matter turns the photon spin angular momentum into an efficient tool for selective trapping of chiral particles. This is demonstrated, both experimentally and theoretically, by exploring the three-dimensional optical trapping of chiral liquid crystal microspheres with circularly polarized Gaussian or Laguerre-Gaussian beams. These results suggest the development of novel optomechanical strategies that rely on the photon helicity towards selective trapping and manipulation of chiral objects by chiral light.