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

Abstract

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.