Abstract
Continuous, wide field-of-view, high-efficiency, and fast-response beam steering devices are desirable in a plethora of applications. Liquid crystals (LCs)—soft, bi-refringent, and self-assembled materials which respond to various external stimuli—are especially promising for fulfilling these demands. In this paper, we review recent advances in LC beam steering devices. We first describe the general operation principles of LC beam steering techniques. Next, we delve into different kinds of beam steering devices, compare their pros and cons, and propose a new LC-cladding waveguide beam steerer using resistive electrodes and present our simulation results. Finally, two future development challenges are addressed: Fast response time for mid-wave infrared (MWIR) beam steering, and device hybridization for large-angle, high-efficiency, and continuous beam steering. To achieve fast response times for MWIR beam steering using a transmission-type optical phased array, we develop a low-loss polymer-network liquid crystal and characterize its electro-optical properties.
Highlights
Positioning a laser beam or light ray is crucial for practical applications, such as light detection and ranging (LiDAR) [1,2,3], displays [4,5,6], microscopy [7], optical tweezers [8], and laser micro-machining [9]
We review recent advances in Liquid crystals (LCs)-based beam steering device technology
With our low-loss polymer-network liquid crystal, a transmission-type LC phase modulator with a relatively fast response time and workable operation voltage can be achieved for mid-wave infrared (MWIR) applications
Summary
Positioning a laser beam or light ray is crucial for practical applications, such as light detection and ranging (LiDAR) [1,2,3], displays [4,5,6], microscopy [7], optical tweezers [8], and laser micro-machining [9]. LCs are self-assembled soft materials, consisting of certain anisotropic molecules with orientational orders They can respond to various external stimuli, including heat, electric and magnetic fields, and light [29,30,31,32]. In the presence of an electric field, LC directors can be re-oriented, due to both the optical and dielectric anisotropies of the LC molecules, resulting in refractive index modulation (bi-refringence) Using this simple principle, LC spatial light modulators (SLMs)— called LC optical phased arrays (OPAs)—can be established by pixelating such refractive index modulators in a two-dimensional (2D) array [33]. With our low-loss polymer-network liquid crystal, a transmission-type LC phase modulator with a relatively fast response time and workable operation voltage can be achieved for mid-wave infrared (MWIR) applications
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