Pushing the Boundaries of Liquid Crystal-Enabled Technologies and Applications

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Liquid Crystals".

Deadline for manuscript submissions: closed (15 May 2024) | Viewed by 1191

Special Issue Editor

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Guest Editor
1. Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ, UK
2. School of Integrated Circuits and Electronics, Beijing Institute of Technology, Beijing 100081, China
Interests: liquid crystals; azobenzene liquid crystals; phase shifter; phased array antenna; microwave devices; millimeter-wave devices; multilevel inverters; sentiment analysis; contact tracing

Special Issue Information

Dear Colleagues,

Original papers expanding the forefront of liquid crystal research are invited, including novel applications (use cases), systems (subsystems), devices (components), techniques (such as design, modeling, fabrication, and measurement), and materials (synthesis and characterization). Submissions that report a wide range of LC-enabled devices and applications across various wavelengths are encouraged, including microwave and mmWave (from MHz to GHz), THz, infrared, and optical. While incremental improvements in device structures and topologies (planar/non-planar transmission lines, waveguides, and a mix) have been targeted over the past three decades, this Special Issue particularly invites submissions on recent successes in theoretical considerations (discovering new mechanisms of device physics and chemistry), advancements in modulation and tuning methods (e.g., LC-driven optical, thermal, and a mix of quasi-electrostatic with photo-chemical methods), as well as experimental validation in pushing the boundaries of device/chip manufacturing and unconventional material synthesis/characterization. Collectively, the data and new methodology presented in this Special Issue are expected to underpin a significant performance improvement and/or cost reduction of LC-enabled technology for commercialization by leveraging cross-disciplinary innovation and multi-objective optimization, i.e., fusing electromagnetism, optics, photonics, photochemistry, thermodynamics, etc.

Dr. Jinfeng Li
Guest Editor

Manuscript Submission Information

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  • liquid crystals
  • liquid crystal beam steering
  • liquid crystal devices and sensors
  • liquid crystal at GHz and THz
  • liquid crystal optics and photonics
  • photosensitive liquid crystals
  • liquid crystal driving and alignment
  • liquid crystal transmission line and waveguide
  • liquid crystal synthesis and characterization

Published Papers (1 paper)

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21 pages, 12673 KiB  
Modeling 0.3 THz Coaxial Single-Mode Phase Shifter Designs in Liquid Crystals with Constitutive Loss Quantifications
by Jinfeng Li and Haorong Li
Crystals 2024, 14(4), 364; https://doi.org/10.3390/cryst14040364 - 11 Apr 2024
Viewed by 814
This work proposes and examines the feasibility of next-generation 0.3 THz phase shifters realized with liquid crystals (LCs) as tunable dielectrics coaxially filled in the transmission line. The classic coaxial transmission line topology is robust to electromagnetic interference and environmental noise, but is [...] Read more.
This work proposes and examines the feasibility of next-generation 0.3 THz phase shifters realized with liquid crystals (LCs) as tunable dielectrics coaxially filled in the transmission line. The classic coaxial transmission line topology is robust to electromagnetic interference and environmental noise, but is susceptible to higher-order modes from microwave to millimeter-wave towards terahertz (THz) wavelength ranges, which impedes the low-insertion-loss phase-shifting functionality. This work thus focuses primarily on the suppression of the risky higher-order modes, particularly the first emerging TE11 mode impacting the dielectric loss and metal losses in diverse manners. Based on impedance matching baselines at diverse tuning states of LCs, this work analytically derives and models two design geometries; i.e., design 1 for the coaxial geometry matched at the isotopically referenced state of LC for 50 Ω, and design 2 for geometry matched at the saturated bias of LC with the maximally achievable permittivity. The Figure-of-Merit for design 1 and design 2 reports as 35.15°/dB and 34.73°/dB per unit length, respectively. We also propose a constitutive power analysis method for understanding the loss consumed by constitutive materials. Notably, for the 0.3 THz design, the isotropic LC state results in an LC dielectric loss of 63.5% of the total input power (assuming 100%), which becomes the primary constraint on achieving low-loss THz operations. The substantial difference in the LC dielectric loss between the isotropic LC state and saturated bias state for the 0.3 THz design (35.76% variation) as compared to that of our past 60 GHz design (13.5% variation) indicates that the LC dielectric loss’s escalating role is further enhanced with the rise in frequency, which is more pronounced than the conductor losses. Overall, the results from analytical and finite-element optimization in this work shape the direction and feasibility of the unconventional THz coaxial phase shifting technology with LCs, actioned as continuously tunable dielectrics. Full article
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