Switchable 3D liquid crystal grating generated by periodic photo-alignment on both substrates

Nys, Inge; Beeckman, Jeroen; Neyts, Kristiaan

doi:10.1039/c5sm01294e

Cited by 48 publications

(52 citation statements)

References 30 publications

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“…More recently, multi-twist structures [75] and twisted-nematic diffractive waveplates [76,77] have been proposed and were demonstrated to show a broader bandwidth (from visible to infrared), in comparison with traditional PBDs. Furthermore, 2D PBDs [78][79][80][81], which can diffract beams into multiple directions, have recently emerged. In addition to varying the diffraction orders, there have been other proposals to change the period by using a sophisticated design of the alignment layer and electrodes [82].…”

Section: Pancharatnam-berry Phase Deflecctorsmentioning

confidence: 99%

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

et al. 2019

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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.

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Section: Pancharatnam-berry Phase Deflecctorsmentioning

confidence: 99%

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

et al. 2019

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“…[97] The patterns are the same for each substrate but they are rotated over 90° compared to each other. It is worth noting that, by using a high symmetry LC such as the nematic, one can fabricate such grating by manipulating the surface anchoring condition only.…”

Section: Surface Template and Electric Field-driven Gratingsmentioning

confidence: 99%

“…A photosensitive alignment layer was spin coated on both substrates limiting a nematic sample and illuminated with interfering UV light of right and left handed polarizations. [97] The patterns are the same for each substrate but they are rotated over 90° compared to each other. Upon filling E7 (an eutectic mixture of several alkyl and alkoxy cyanobiphenyls and cyanoterphenyl derivative) material into the cell, a complex 3D pattern with double periodicity is observed, and, when a probe laser is used, a 2D diffraction pattern appears, being field controllable with high efficiency, thanks to the overall quality of the structure.…”

Section: Surface Template and Electric Field-driven Gratingsmentioning

confidence: 99%

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

et al. 2018

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the duality consolidation, the idea of controlling light and how it interacts with matter has always been an exciting topic. Visible light, as we perceive it, is a small portion of the electromagnetic spectrum composed of mutually perpendicular oscillating electric and magnetic fields that propagate through space and presents wave-like and particle-like behavior. Since the elements comprising matter possess dynamic electron clouds, the electromagnetic nature of light prompts different responses when it interacts with different materials, depending on its intensity, frequency, the arrangement of molecules, and so on. Whenever light interacts with matter, it might be absorbed, re-emitted, scattered, or transmitted. Although these effects are well known, the combination of them with new, innovative materials pushes optics forward. In fact, advances in optics have often occurred through the development of materials with improved optical properties, thus creating remarkable applications that tremendously influence our daily lives. These exciting applications include image processing and recording, lasing, data storage, display devices, detector systems, propulsion systems, and optical tweezers, which have enabled remote micromanipulation of colloidal particles and promising applications in various biomedical and biological applications. [1][2][3] There is, however, one component that stands out: the diffraction grating. It is generally regarded as one of the most important devices in the development of several fields of science. [4] Such importance comes from the fact that a diffraction grating is a device with a periodic structure capable of changing the propagation and splitting the spectrum The ability to control light direction with tailored precision via facile means is long-desired in science and industry. With the advances in optics, a periodic structure called diffraction grating gains prominence and renders a more flexible control over light propagation when compared to prisms. Today, diffraction gratings are common components in wavelength division multiplexing devices, monochromators, lasers, spectrometers, media storage, beam steering, and many other applications. Next-generation optical devices, however, demand nonmechanical, full and remote control, besides generating higher than 1D diffraction patterns with as few optical elements as possible. Liquid crystals (LCs) are great candidates for light control since they can form various patterns under different stimuli, including periodic structures capable of behaving as diffraction gratings. The characteristics of such gratings depend on several physical properties of the LCs such as film thickness, periodicity, and molecular orientation, all resulting from the internal constraints of the sample, and all of these are easily controllable. In this review, the authors summarize the research and development on stimuli-controllable diffraction gratings and beam steering using LCs as the active optical materials. Dynamic gratings fabricated by applying external f...

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“…Photo-alignment makes use of (polarized) illumination to obtain a preferential LC orientation. Different illumination techniques (direct write, holography, plasmonic patterning) were optimized in recent years to obtain high-resolution, high-throughput and repeatable patterns with a low cost [8][9][10][11][12][13][14]. Photo-alignment is a very versatile method, but the spatial resolution is limited and the period of the alignment pattern should be above several hundred nanometer.…”

Section: Introductionmentioning

confidence: 99%

Voltage-controlled formation of short pitch chiral liquid crystal structures based on high-resolution surface topography

Nys¹,

Beeckman²,

Neyts³

2019

Opt. Express

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Chiral nematic liquid crystals (CLCs) offer interesting perspectives for device applications and are fascinating materials to study because of their ability to self-assemble into complex structures. This work demonstrates that narrow lines of electron-beam resist on top of an ITO coated glass surface can dramatically influence the formation and growth of short pitch chiral superstructures in the bulk. By applying a voltage to the cell, directional growth of CLC structures along the corrugated surface can be controlled. Below the electric unwinding threshold, chiral structures start to grow along the grating lines with their helical axis parallel to the substrates. This results in a uniform lying helix-like structure at intermediate voltages and a chiral configuration with periodic undulations of the helical axis at low voltages.

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Switchable 3D liquid crystal grating generated by periodic photo-alignment on both substrates

Cited by 48 publications

References 30 publications

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

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

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

Voltage-controlled formation of short pitch chiral liquid crystal structures based on high-resolution surface topography

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