Arbitrary Beam Steering Enabled by Photomechanically Bendable Cholesteric Liquid Crystal Polymers

Abstract

Beam-steering technology is now in widespread use in a variety of optical systems, spanning from fiber-optic interconnector to Lidar. Most current techniques are based on optical grating diffractions; they are thus subject to not only finite tuning range, direction, and efficiency but also complex inorganic fabrication and circuit design. A high-degree-of-freedom beamsteering element makes such operations more efficient and versatile. Azobenzene cholesteric liquid crystal polymer (azo-ChLCP) can be regarded as a soft self-assembled Bragg mirror capable of being bent photomechanically. With proper control of pump polarization and exposure time, the output beam can be directly steered to an arbitrary direction. The deflection efficiency was achieved to be at least 90% with an angular tuning range of ≈54°, which is markedly superior to conventional grating-based devices. Additionally, the angle of deflection is independent of wavelength, preventing the deflected beam from spreading out with colors. This work demonstrates and characterizes the azo-ChLCP beam deflector, which features optical tunability, high efficiency, wide tuning range, and polarization-selective deflection direction, making a significant breakthrough in beam-steering technology.

Travelling waves on photo-switchable patterned liquid crystal polymer films directed by rotating polarized light

“…22,56 Here, we assume the order parameter to be constant (S = 0.8), since the loss of order in heavily-crosslinked glassy LC polymers is usually found to be small. 22,25,37 One can get the temporal evolution of the trans and cis fractions and the local intensity by solving the coupled partial differential eqn (1) and (2) subject to the boundary condition Iðw; tÞ ¼ 1 and the initial condition n t (z,0) = 1. The time needed to reach an equilibrium (photo-stationary) state for the deformation is observed to be fast for glassy LC polymers, typically in the range of a few seconds.…”

“…We take advantage of the selective absorption of the azobenzenes when oriented parallel to the electric field of the polarized light. 24,[36][37][38] As schematically shown in Fig. 1(c and d), the directors are all confined in the plane parallel to the substrate and feature a continuous rotation in the direction of the x axis, see Fig.…”

Liquid Crystal Beam Steering Devices: Principles, Recent Advances, and Future Developments

“…Here, we make clear that the research into LC-based beam steering is still ongoing. Apart from the above-mentioned options, other scientifically intriguing approaches have also emerged [37,38]. For instance, by combining micro-mirrors with LC elastomer fibers, it is possible to create a beam steering device which responds to external stimuli, such as light [37].…”

Light‐Activated Liquid Crystalline Hierarchical Architecture Toward Photonics

“…Moreover, a special bilayer LC cell was also designed and a light‐induced diffraction dimensionality transformation was achieved, including 1D and 2D diffraction states and a diffraction off state. The aforementioned photoresponsive materials and controlling methods put forward new strategies for designing controllable diffractive elements as well as their applications …”