The Birefringence and Extinction Coefficient of Ferroelectric Liquid Crystals in the Terahertz Range

Ying Ma; Yuhang Shan; Yongning Cheng; Ruisheng Yang; Hoi-Sing Kwok; Jianlin Zhao

doi:10.3390/photonics10121368

Photonics (Dec 2023)

The Birefringence and Extinction Coefficient of Ferroelectric Liquid Crystals in the Terahertz Range

Ying Ma,
Yuhang Shan,
Yongning Cheng,
Ruisheng Yang,
Hoi-Sing Kwok,
Jianlin Zhao

Affiliations

Ying Ma: Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, School of Physics Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
Yuhang Shan: Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, School of Physics Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
Yongning Cheng: Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, School of Physics Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
Ruisheng Yang: MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China
Hoi-Sing Kwok: State Key Laboratory (SKL) on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Kowloon 999077, Hong Kong
Jianlin Zhao: Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, School of Physics Science and Technology, Northwestern Polytechnical University, Xi’an 710129, China

DOI: https://doi.org/10.3390/photonics10121368
Journal volume & issue: Vol. 10, no. 12
p. 1368

Abstract

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In this paper, the refractive index and extinction coefficient of ferroelectric liquid crystals have been examined by the terahertz time-domain spectroscopy system. Two modes of ferroelectric liquid crystal materials, deformed helix ferroelectric liquid crystal (DHFLC), and electric suppressed helix ferroelectric liquid crystal (ESHFLC) are tested as experimental samples. Nematic liquid crystal (NLC) was also investigated for comparison. The birefringence of DHFLC 587 slowly increases with the growth of frequency, and it averages at 0.115. Its extinction coefficients gradually incline to their stable states at 0.06 for o-wave and 0.04 for e-wave. The birefringence of ESHFLC FD4004N remains between around 0.165 and 0.175, and both of its e-wave and o-wave extinction coefficients are under 0.1, ranging from 0.05 to 0.09. These results of FLC will facilitate the examination and improve the response performance of THz devices using fast liquid crystal materials.

Published in Photonics

ISSN: 2304-6732 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Engineering (General). Civil engineering (General): Applied optics. Photonics
Website: http://www.mdpi.com/journal/photonics

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