Generation of controllable chiral optical fields by vector beams
Chirality is common in nature, describing not only the geometrical property of a three-dimensional object, but also an intrinsic feature of an optical field. Chiral optical fields are acquiring increasing attention due to their potential applications in chiral light-matter interaction. Here we demonstrate a strategy to realize a controllable chiral optical field by tightly focusing two tailored vector beams in a 4π optical microscopic system. By modulating the wavefronts of the incident vector beams with properly designed phase masks, a chiral optical field with multiple spots carrying switchable handedness or controllable chirality can be generated. The location, the number and the handedness of such chiral spots can be arbitrarily adjusted depending on the actual application requirements. In addition to multiple particles trapping and manipulating, this controllable chiral optical field may find applications in enantioselective separation, chiral detection and chiral sensing at the nanoscale.