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Proceedings Paper

Recent advances in IR liquid crystal spatial light modulators
Author(s): Fenglin Peng; Robert J. Twieg; Shin-Tson Wu
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Paper Abstract

Liquid crystal (LC) is an amazing class of electro-optic media; its applications span from visible to infrared, millimeter wave, and terahertz regions. In the visible and short-wavelength infrared (SWIR) regions, most LCs are highly transparent. However, to extend the electro-optic application of LCs into MWIR and LWIR, several key technical challenges have to be overcome: (1) low absorption loss, (2) high birefringence, (3) low operation voltage, and (4) fast response time. In the MWIR and LWIR regions, several fundamental molecular vibration bands and overtones exist, which contribute to high absorption loss. The absorbed light turns to heat and then alters the birefringence locally, which in turns causes spatially non-uniform phase modulation. To suppress the optical loss, several approaches have been investigated: (1) Employing thin cell gap by choosing a high birefringence LC mixture; (2) Shifting the absorption bands outside the spectral region of interest by deuteration, fluorination, or chlorination; (3) Reducing the overtone absorption by using a short alkyl chain. In this paper, we report some recently developed chlorinated LC compounds and mixtures with low absorption loss in the SWIR and MWIR regions. To achieve fast response time, we demonstrated a polymer network liquid crystal with 2π phase change at MWIR and response time less than 5 ms. Approaches to extend such a liquid crystal spatial light modulator to long-wavelength infrared will be discussed.

Paper Details

Date Published: 5 September 2015
PDF: 6 pages
Proc. SPIE 9565, Liquid Crystals XIX, 95650M (5 September 2015); doi: 10.1117/12.2190697
Show Author Affiliations
Fenglin Peng, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Robert J. Twieg, Kent State Univ. (United States)
Shin-Tson Wu, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)

Published in SPIE Proceedings Vol. 9565:
Liquid Crystals XIX
Iam Choon Khoo, Editor(s)

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