Broadband circular birefringence with reconfigurable metasurface systems

Chirality is an intrinsic symmetry property of three-dimensional systems and arises when the system is distinguishable from its mirror image. New chiral systems capable of specifying and actively tuning circular birefringence would have broad implications in sensing, polarimetry, active quantum control, optical information processing, and communications. We present a reconfigurable chiral metasurface system that uses the shear displacement between two Pancharatnam-Berry metagratings to produce tailored broadband circular birefringence responses. Our dual metasurfaces give rise to a system that can break three-dimensional symmetry in order produce configurations ranging from achiral to chiral.