Optimizing low frequency electro-optic response of nematic liquid crystals

Hassanein, G. Nabil

doi:10.1016/j.ijleo.2019.01.036

Cited by 6 publications

(3 citation statements)

References 19 publications

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“…In our previous study [21,22], an amplitude modulated (AM) electric signal was applied to enhance the electro-optic response of liquid crystals by increasing the modulating signal frequency. High modulating frequency, 100 Hz, was applied in this study with all samples that are homogeneously aligned in cells of thickness 5 m.…”

Section: Electro-optical Measurementsmentioning

confidence: 99%

“…Since both also have the other desirable parameters for applications including low viscosity, modest dielectric anisotropy, proper elastic constants, and good material stability for long-term operation. When proper combination of the applied field strength and modulating frequency of an amplitude modulating (AM) driving applied electic signal is applied on NLC sample; electrooptic properties are improved applying a relatively low applied voltages [21,22]. Also proper mixing of two NLCs with certain mixing ratios can improve effectively the electrooptic properties of a proper binary mixture of both 7CB and PCH5 under the effect of an AM electrical signal.…”

Section: Introductionmentioning

confidence: 99%

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Binary Nematic Liquid Crystals Mixture with Enhanced Electro-Optics Properties for Photonic Applications

Hassanein,

Alhaddad,

Ellabban

2024

AJPS

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Purpose: In this work, we mix two simple nematic liquid crystals (NLCs) and investigated the binaryNLCs mixtures of 7CB/PCH5 of different mixing ratios. Methodology: The pure liquid crystals 7CB and PCH5 and binary mixtures of them of high temperature stability were thermally analyzed by differential scanning calorimetry. The mixture 7CB/PCH5:30/70 wt% has the highest thermal stability with a nematic-isotropic (N-I) transition temperature at 50oC. The electrooptic properties of 7CB, PCH5, and the mixture 7CB/PCH5:30/70 wt% at room temperature were also investigated using an amplitude modulated electric signal (1 kHz - 100 Hz) by increasing diving peak voltage from 0 V to 10 V. The threshold volage is relatively reduced for the binary mixture in comparison to that value for PCH5. In comparison to the pure LCs, the mixture 7CB/PCH5:30/70 wt% has the fastest response times of values 2.36 ms total time response, 0.41 ms rise time, and 1.95 ms fall time. It has also the highest contrast ratio. Moreover, it has a maximum measured transmission that is higher than those for PCH5 and 7CB by about 17 % and 8%, respectively, at a field strength of 2V/mm. Findings: The obtained results indicate that the electrooptic properties of PCH5 was improved when mixed with a proper ratio of 7CB, of lower cost, more stablity , and higher potential for photonic applications. Unique Contriburibution to Theory, Practice and Policy: This expermental study shows that simply by mixing two relatively low cost NLCs materials, one of high thermal stability and low electro-optic properties with other one of low thermal stability and better electro-optic properties; this would improve the stability, response, and transmition of the binary mixture. If the a suitable driving method is applied, without doping with other orgnic or inorganic matrial.

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Section: Electro-optical Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Binary Nematic Liquid Crystals Mixture with Enhanced Electro-Optics Properties for Photonic Applications

Hassanein,

Alhaddad,

Ellabban

2024

AJPS

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“…The BK7 material has high thermal stability as reported in 35 , 40 Thus, the temperature has approximately no effect on the optical characteristics of the BK7 core. Additionally, the light propagation in the left core of the presented structure will not be affected by the external applied voltage where the BK7 material is electrically stable and has no electro-optic effects 35 , 47 .…”

Section: Introductionmentioning

confidence: 99%

Asymmetric dual-core liquid crystal channel-based tunable mode converter

Esmail,

Hameed,

Obayya

et al. 2024

Sci Rep

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In this work, a higher order-to-fundamental mode converter is reported and analyzed based on an asymmetric dual channel waveguide (ADC-WG) on silicon. In the reported structure, one of the two waveguides is infiltrated with nematic liquid crystal (NLC) material to add temperature tunability while the other one is a solid BK7 waveguide. The modal characteristics are obtained using the full vectorial finite difference method (FVFDM). In addition, the structural parameters and optical characteristics of the employed materials are investigated to achieve good wavelength selectivity with a short device length (LD). Thus, a compact mode converter that can work at different wavelengths including the telecommunication wavelength i.e., 1.55 μm with LD ~ 482.31 μm and a low crosstalk of − 19.86 dB is presented. To prove the thermal tunability of the suggested mode converter, its operation is tested through a temperature range between 20 and 35 °C and the results show that the mode conversion process is achieved at each temperature with different phase matching wavelengths (λPMW) but with quite similar coupling length (LC). The proposed device can therefore be effectively utilized in integrated photonic circuits.

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Analysis of factors influencing about the effects of the liquid crystal micro fluid drive

Sun,

Liu

2023

Ferroelectrics

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Optimizing low frequency electro-optic response of nematic liquid crystals

Cited by 6 publications

References 19 publications

Binary Nematic Liquid Crystals Mixture with Enhanced Electro-Optics Properties for Photonic Applications

Binary Nematic Liquid Crystals Mixture with Enhanced Electro-Optics Properties for Photonic Applications

Asymmetric dual-core liquid crystal channel-based tunable mode converter

Analysis of factors influencing about the effects of the liquid crystal micro fluid drive

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