Tunable band-pass optical vortex processor enabled by wash-out-refill chiral superstructures

The manipulation of spatial parameters of light is at the cutting edge of optics. It is an interesting and important task to explore wavefront modulation approaches with a continuously tunable working band and dynamically switchable functions. Here, we program the alignment of a polymerizable cholesteric liquid crystal by a dynamic photo-patterning technique. After UV curing and a wash-out-refill process, the designed chiral superstructure is well reconstructed. By this means, a Dammann grating encoded q-plate is fabricated and its function as an optical vortex processor is demonstrated. The working band is electrically tuned and covers a broad range of 137 nm. The switching of mode conversion is achieved on a second scale for given wavelengths based on the electric-driven band shift. This strategy offers a platform for multi-dimensional dynamic control of light and may bring more possibilities to optical imaging, informatics, and micromanipulations.