Liquid-crystal metasurfaces: Self-assembly for versatile optical functionality

Abstract

Liquid crystals subjected to modulated surface alignment assemble into metasurface-type structures capable of various flat-optical functionalities, including light diffraction and focusing, deflection and splitting. Remaining in a fluid phase, they are susceptible to external stimuli, and, in particular, can be efficiently controled by low voltages. We overview the existing approaches to the design and fabrication of liquid-crystal metasurfaces, highlight their realized optical functions and discuss the applied potential in emerging photonic devices.

New quasiperiodic structures in nematic liquid crystals

“…[5][6][7][8][9] Since the discovery of domain walls, topological defects have become a robust field of LC research, with extensive reviews, [10][11][12][13] in addition to the expansive field of LC display applications. [14][15][16][17][18][19][20][21][22][23] Domain walls have been shown to reduce into a pair of disclination lines at a critical field strength, in the pincement process. 24 Newer experiments and theoretical work have reported on velocity of the front to expand the knowledge of this phenomena.…”

Multifunctional Metasurface Tuning by Liquid Crystals in Three Dimensions

“…To date, various tuning mechanisms have been successfully demonstrated, such as the use of phase-change materials, − mechanical stretching, − the injection of free-carriers, , and the use of thermo-optical effects . Among these, the integration of optical metasurfaces into liquid crystal (LC) cells has proven to be a successful strategy for realizing pronounced metasurface resonance tuning. − Because of their optical birefringence, i.e., the difference between the ordinary ( n o ) and extraordinary ( n e ) refractive indices, integrating LCs with metasurfaces provides an avenue to actively tune the optical properties of a device after fabrication. Utilizing this opportunity, it has been demonstrated that LC metasurfaces can be tuned with various stimuli, such as by changing the temperature or by applying an external electric field. ,,, The use of an external voltage together with temperature has also been suggested to further enhance the functionality of devices based on metasurfaces .…”