Broad spectrum measurement of the birefringence of an isothiocyanate based liquid crystal

Abstract

(2010) Broad spectrum measurement of the birefringence of an isothiocyanate based liquid crystal. Applied Optics, 49 (28). pp. 5212-5216. Permanent WRAP URL:http://wrap.warwick.ac.uk/92169 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement:© 2010 Optical Society of America]. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved. A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription.

Highly birefringent, low-loss liquid crystals for terahertz applications

“…Theoretical predictions of the far-infrared vibrational spectrum as well as ultrabroadband experimental spectroscopic data, which, for example, were recently reported for 5 CB, 32 may help to verify this assumption. While other LC systems exhibiting a comparably high birefringence have been reported recently, 33 these structures typically suffer from high dichroism, thus limiting the application for switchable components significantly. The average absorption coefficient of 1852, i.e., the mean value of ordinary and extraordinary absorption coefficients, is therefore much lower than that of LCs with comparably high birefringence reported at THz frequencies so far.…”

THz characterization of a metamaterial-based spatial light modulator

“…2 (b) shows the results of the e.m. full-wave calculations compared with the experimental results for both the base layer and the complete (quasi-3D) structure. In the simulation, we assumed that the liquid crstal was fully isotropic with a value of the refractive index n iso = [(n| | 2 + 2n⊥ 2 )/3] 1/2 = 1.65 [12]. A very good agreement between simulations and measurements is observed.…”

“…For the test, we choose as liquid crystal an isothiocyanate based mixture having low absorption coefficient α and high birefringence Δn (Δn = n| | -n⊥, where n| | and n⊥ are the extraordinary and ordinary refractive indices respectively) in the THz region. At 1.5 THz and room temperature, this LC has α values in the range 10 ÷ 50 cm -1 and Δn as high as 0.3 [12]. Indeed, due to the LC infiltration, a red frequency shift of 160 GHz and signal modulation depth up to 20 dB at the central frequency is observed.…”

High-birefringence nematic liquid crystal for broadband THz applications

“…According to Reuter et al [28], LCs with NCS groups enable higher birefringence over a broad temperature range than CN groups and have rather low viscosity. This material has been studied by Trushkevych et al [29], but they did not use very efficient alignment schemes such as high voltage and the THz band they measured is limited to 0.5-1.6 THz. In our 0.2-2.5 THz spectrum ( Figure 5), LCMS-107 shows a high birefringence (~0.3) across the entire band.…”