Ultra-Broadband Tunable Bragg-Berry Optical Vortex Generators of a Circularly Symmetric Chiroptic Structure

New optical-photonic devices with the capability to manipulate, modify, and even tailor the light characteristics dynamically, such as wave surface, play an increasingly important role in the development of modern and future optics. Optical vortex with spiral wave surfaces is a special type of light with intrinsic orbital angular momentum (OAM). Thus, this vortex can be applied to the development of advanced optics, such as optical tweezers, ultra-resolution microscope, optical communication, and quantum technology. This study demonstrates an optical device known as Bragg-Berry optical vortex generator (BBOVG) with a circularly symmetric chiral photonic structure using an easy-to-implement method by filling a ferroelectric liquid crystal-doped cholesteric liquid crystal (FLC-CLC) material into an indium-tin-oxide-coated cell pre-treated with photoalignment along the azimuthal direction. The BBOVG devices can be operated by dynamically tuning the photonic bandgaps of the opposite-handed FLC-CLCs throughout the full-visible region (400-700 nm) in a low voltage range (<= 3.0 V) to obtain reflective optical vortices with opposite OAM signs in a full-visible range near room temperature. The present devices, which can transform geometric phase and have ultra-wideband manipulability and high operability at room temperature, provide a good example in demonstrating key devices that fit the use in future optical/photonic applications.

Automated summary

New optical-photonic devices that can manipulate light characteristics dynamically are crucial for modern and future optics development. Optical vortex with spiral wave surfaces, which possess intrinsic orbital angular momentum, can be applied in advanced optics like optical tweezers, ultra-resolution microscopes, optical communication, and quantum technology. The study presents a Bragg-Berry optical vortex generator (BBOVG) made of a circularly symmetric chiral photonic structure using a simple method, demonstrating the manipulation of reflective optical vortices with opposite OAM signs in the visible range near room temperature.