Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles

Xiang, Xiao; Kim, Jihwan; Escuti, Michael J.

doi:10.1038/s41598-018-25535-0

Cited by 60 publications

(40 citation statements)

References 21 publications

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“…Meanwhile, the index contrast of the coupler determines the angular and spectral responses, especially for grating and hologram, which affects the color uniformity over the FOV and the eye-box ( Kress, 2019 ). Due to the significant impact of the coupler on the system, numerous technologies have been applied to optimize the coupler performance ( Xiang et al., 2018 ; Gao et al., 2017 ; Yin et al., 2019 ; Yin et al, 2020b ). As a result, the angular response of an LNED system is not limited by the coupler but by the critical angle of TIR, which is in turn determined by the lightguide refractive index.…”

Section: Ar: Field Of Viewmentioning

confidence: 99%

Augmented Reality and Virtual Reality Displays: Perspectives and Challenges

et al. 2020

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Summary As one of the most promising candidates for next-generation mobile platform, augmented reality (AR) and virtual reality (VR) have potential to revolutionize the ways we perceive and interact with various digital information. In the meantime, recent advances in display and optical technologies, together with the rapidly developing digital processers, offer new development directions to advancing the near-eye display systems further. In this perspective paper, we start by analyzing the optical requirements in near-eye displays poised by the human visual system and then compare it against the specifications of state-of-the-art devices, which reasonably shows the main challenges in near-eye displays at the present stage. Afterward, potential solutions to address these challenges in both AR and VR displays are presented case by case, including the most recent optical research and development, which are already or have the potential to be industrialized for extended reality displays.

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Section: Ar: Field Of Viewmentioning

confidence: 99%

Augmented Reality and Virtual Reality Displays: Perspectives and Challenges

et al. 2020

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“…The field of view (angular response) for the central wavelength is around 20 • . Fortunately, by applying multi-layer structures, both spectral and angular bandwidths can be dramatically increased while keeping a high diffraction efficiency [92].…”

Section: Fast Response Time For Mwir Beam Steeringmentioning

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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“…The mixture was filled into a planar rubbed cell and, before photopolymerization, an electric field used to drive the planar oriented CLC to the LH configuration. [240] Polymer templating was also demonstrated in Bragg gratings, [241] in polymer stabilized phase gratings, [242] and in microgratings, which were fabricated by exposing the CLC material under an electric field to a Gaussian UV laser of desirable size. Another advantage of polymerization is the fact that it considerably improves the diffraction efficiency, the authors reporting up to 75% efficiency.…”

Section: Polymer Mediatedmentioning

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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Bragg polarization gratings for wide angular bandwidth and high efficiency at steep deflection angles

Cited by 60 publications

References 21 publications

Augmented Reality and Virtual Reality Displays: Perspectives and Challenges

Augmented Reality and Virtual Reality Displays: Perspectives and Challenges

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

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

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