Dear Colleagues,

Liquid-crystal polarization gratings (LCPGs) are attracting wide interest in both the liquid crystal and optics fields due to their intriguing formation process, unique optical properties, and potential applications in emergent wearable devices, such as augmented/virtual reality headsets.

Depending on the formation process, LCPGs can be categorized into two major types. The first method utilizes polarization interference to pattern a thin photo-alignment layer, and the subsequently coated/filled liquid crystals can self-align into gratings following the patterned surface. The second method utilizes the photocycloaddition of cinnamate moieties or similar processes to record the volumetric polarization field during polarization interference into the body of the material and then subject it to an annealing process to induce birefringence. The behaviors of LCPGs are highly dependent on materials and interference patterning and processing. In the simplest case, linear gratings can be formed, while complicated, exotic gratings may also be generated. In the past, a significant amount of effort has been focused on liquid crystal research on electrically switchable non-polymer liquid crystal materials for display, phase modulation, or shutter applications. Polymerizable materials, molecular kinematics, and the consequent optical properties for both types of LCPGs are comparatively still an uncharted territory, with new challenges and opportunities.

The unique properties of LCPGs open new possibilities in various fields, such as imaging, display, beam-shaping, beam-steering, communication, sensing, spectroscopy, AR/VR, etc. With new optical components, it is an exciting time to explore novel optical systems that tackle these challenges and rethink classic optical designs.

This Special Issue of Crystals serves to provide a platform for researchers to report results and findings in liquid-crystal or liquid-crystal-polymer LCPGs in the aspects of material, processing, patterning, polymerization, molecular kinematics, optical properties, and their applications.

Potential topics include but are not limited to:

• Materials for LCPGs;
• Interplay between materials and LCPGs structures;
• Effect of processing and patterning on LCPGs;
• Optical characteristics of LCPGs;
• Novel structures of LCPGs;
• Applications of LCPGs;
• Optical systems based on LCPGs.

Dr. Yishi Weng
Prof. Dr. Jianghao Xiong
Prof. Dr. Chaoping Chen
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• liquid-crystal gratings
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• Liquid-Crystal Polarization Gratings in Crystals (9 articles)