Effect of Temperature on the Refractive Indices of Liquid Crystals and Validation of a Modified Four-Parameter Model

Thingujam, Kiranmala; Sarkar, Suchismita Datta; Choudhury, Basana; Bhattacharjee, Ayon

doi:10.12693/aphyspola.122.754

Cited by 28 publications

(12 citation statements)

References 24 publications

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“…He−Ne la− ser (l = 633 nm) beam was used to get two refracted spots from the LC−filled prism corresponding to extraordinary and ordinary rays on a screen placed at a distance of about 5 meters from the prism. The details are reported elsewhere [10,11]. The images of the spots were photographed using a high resolution digital camera and those images were ana− lysed, and the data obtained were used to calculate the re− quired refractive indices.…”

Section: Methodsmentioning

confidence: 99%

“…The effect of temperature on the refractive indices and birefringence is critically important for display devices. In order to establish a relationship of the temperature dependence of LC refractive indices, various theoretical models [6][7][8][9], as well as several experimental techniques [10][11][12][13][14] have been developed. From the study of refractive indices of liquid crystals, it is possible to obtain information on anisotropy of the light waves traversing through them [15].…”

Section: Introductionmentioning

confidence: 99%

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Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

Devi

Choudhury

Bhattacharjee

et al. 2014

Opto-Electronics Review

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Optical studies have been carried out on two fluorinated isothiocyanato nematic liquid crystal (LC) compounds 4′-butylcyclohexyl-3, 5-difluoro-4-isothiocyanatobiphenyl and 4′-pentylcyclohexyl-3, 5-difluoro-4-isothiocynatobiphenyl. Transition temperatures of the two samples were confirmed using a polarizing microscope. The two LC compounds were found to exhibit fairly high clearing temperatures. Measurements of refractive indices of the two compounds were done by using thin prism method with He-Ne laser beam of wavelength 630 nm. Birefringence of the two LC compounds was calculated from the measured refractive indices. Both the compounds are found to display fairly high values of birefringence. Validation of a modified four-parameter model, based on Vuks equation describing the temperature dependence of refractive indices of the two liquid crystals, is also presented in this paper. The model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the two nematic LCs with the theoretical values. In this paper, the calculation of order parameters of the LCs is presented by using two methods: direct extrapolation method based solely on the birefringence data and by using modified Vuks method based on Haller’s extrapolation. As observed from the obtained results, this procedure of calculating order parameter gives very reasonable results.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

Devi

Choudhury

Bhattacharjee

et al. 2014

Opto-Electronics Review

Self Cite

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“…The dispersion characteristics of the 2CHBT/8CHBT NLC mixture, shown in Fig. 2(a), was obtained by fitting the Cauchy functions to the experimental data (represented by hollow and solid circles) taken from the thin prism me− thod [29]. Thermal dependence of NLC mixture refractive indices has been measured for the wavelength of 589 nm with the use of a refractometer at the MUT [ Fig.…”

Section: Methodsmentioning

confidence: 99%

Light propagation mechanism switching in a liquid crystal infiltrated microstructured polymer optical fibre

Rutkowska

Mileńko

Chojnowska

et al. 2015

Opto-Electronics Review

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In this work studies on propagation properties of a microstructured polymer optical fibre infiltrated with a nematic liquid crystal are presented. Specifically, the influence of an infiltration method on the LC molecular alignment inside fibre air-channels and, thus, on light guidance is discussed. Switching between propagation mechanisms, namely the transition from modified total internal reflection (mTIR) to the photonic bandgap effect obtained by varying external temperature is also demonstrated.

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“…As the temperature increases, ordinary (n o ) and extraordinary (n e ) refractive indices of LCs behave differently from each other [8,9].…”

Section: Introductionmentioning

confidence: 99%

Temperature Effects on Liquid Crystal Nonlinearity

Al-Qurainy¹,

Naimee²

2018

Liquid Crystals - Recent Advancements in Fundamental and Device Technologies

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The effect of temperature variation on nonlinear refractive indices of several types of liquid crystal (LC) compounds has been reported. Five samples have been investigated: two pure components (E7, MLC 6241-000) and three mixtures are obtained by mixing the previous two in different proportions. Birefringence, the average refractive index and the temperature gradients of refractive indices of the LCs are determined. The variations in refractive indices and birefringence were fitted theoretically using the modified Vuks equation. Excellent agreement is obtained between the fitted values and experimental data. Finally, the bistability of nonlinear refractive indices with temperature of liquid crystal (LC) compounds has been studied. The bistability of liquid crystals based on temperature is clearly observed for all samples. Also, the extraordinary refractive index has larger bistability than the ordinary refractive index. The measurements are performed at 1550 nm wavelength using wedged cell refractometer method.

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Effect of Temperature on the Refractive Indices of Liquid Crystals and Validation of a Modified Four-Parameter Model

Cited by 28 publications

References 24 publications

Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

Light propagation mechanism switching in a liquid crystal infiltrated microstructured polymer optical fibre

Temperature Effects on Liquid Crystal Nonlinearity

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