Electrically switchable photonic liquid crystal devices for routing of a polarized light wave

Rushnova, I. I.; Melnikova, E. A.; Толстик, А. Л.; Muravsky, Alexander

doi:10.1016/j.optcom.2017.12.029

Cited by 23 publications

(14 citation statements)

References 15 publications

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“…Except for a small dimension of molecules, the additional benefit of LC devices is a relatively low cost of manufacturing. It is well known that by the electrical voltage it is possible to reorient LC molecules in a predicted way [4,5]. When director of an LC device is reoriented, its optical properties change regarding refractive index changes from ordinary to extraordinary value [6].…”

Section: Introductionmentioning

confidence: 99%

Electro-Steering Tapered Fiber-Optic Device with Liquid Crystal Cladding

et al. 2019

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The paper presents the results of design, manufacturing, and characterization of a hybrid broad band in-line fiber-optic device. It uses nematic liquid crystal as cladding with electro-steering properties in a biconical optical fiber taper structure. Liquid crystal mixtures denoted as 6CHBT and E7 are designed for electric as well as temperature control of electromagnetic wave propagation in a broad wavelength range. The applied taper with 10±0.5 μm diameters has losses lower than 0.5 dB in whole investigated spectrum range. Three kinds of initial liquid crystal molecules’ orientations (parallel, orthogonal, and twist) in relation to the light beam propagating in a taper were applied. The performance of a tuned cladding was studied at an electric field of the range of 0–190 V and the temperature range from 20°C up to 42°C and 59°C for 6CHBT and E7, respectively. The induced reorientation of liquid crystal molecules was measured at a broad wavelength range (550-1550 nm).

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Section: Introductionmentioning

confidence: 99%

Electro-Steering Tapered Fiber-Optic Device with Liquid Crystal Cladding

et al. 2019

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“…Alignment of liquid crystal (LC) molecules along a preferred direction plays a crucial role in the fabrication of the high-performance devices, such as LC displays (LCDs), modulators, light shutters, and sensors. − Thus, controlling LC alignment via tuning the surface environments becomes particularly important in both academic field and engineering application. The most conventional method is mechanical rubbing on the substrate coated with thin organic polymer films. − Although the mechanical rubbing method is simple and robust, the obvious disadvantage is that mechanical frication can easily generate dust particles, mechanical damage, and electrostatic damage, which seriously limits the further application.…”

Section: Introductionmentioning

confidence: 99%

Alignment Control of Nematic Liquid Crystal using Gold Nanoparticles Grafted by the Liquid Crystalline Polymer with Azobenzene Mesogens as the Side Chains

Kuang

Fan

Tao

et al. 2018

ACS Appl. Mater. Interfaces

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The gold nanoparticles highly grafted by a liquid crystalline polymer (LCP) with azobenzene mesogens as the side chain (denoted as Au@TE-PAzo NPs) are successfully designed and synthesized by the two-phase Brust-Schiffrin method. The chemical structures of the monomer and polymer ligands have been confirmed by nuclear magnetic resonance, and the molecular weight of the polymer is determined by gel permeation chromatography. The combined analysis of transmission electron microscopy and thermogravimetric analysis shows that the size of the nanoparticles is 2.5(±0.4) nm and the content of the gold in the Au@TE-PAzo NPs is ca. 17.58%. The resultant Au@TE-PAzo NPs can well disperse in the nematic LC of 5CB. The well-dispersed mixture with appropriate doping concentrations can automatically form a perfect homeotropic alignment in the LC cell. The homeotropic alignment is attributed to the brush formed by Au@TE-PAzo NPs on the substrate, wherein the Au@TE-PAzo NPs gradually diffuse onto the substrate from the mixture. On the contrary, the pure side chain LCPs cannot yield vertical alignment of 5CB, which indicates that the alignment of 5CB is ascribed to the synergistic interaction of the nanoparticles and the grafted LCPs. Moreover, Au@TE-PAzo NPs show excellent film-forming property on account of their periphery of high densely grafted LCPs, which can form uniform thin film by spin-coating. The resultant thin film also can prompt the automatical vertical alignment of the nematic 5CB. Further, upon alternative irradiation of UV and visible light, the alignment of 5CB reversibly switches between vertical and random orientation because of the trans-cis photoisomerization of the azobenzene group on the periphery of Au@TE-PAzo NPs. These experimental results suggest that this kind of nanoparticles can be potentially applied in constructing the remote-controllable optical devices.

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“…The new AtA-2 F I G U R E 6 Dye molecule and surroundings that form a mean field, which compensates for the dipole moment of the molecule 11 F I G U R E 7 Theoretical (solid lines) and experimental (dots) dependences of azimuthal anchoring energy coefficient Wa and dichroic ratio (DR) on exposure dose for liquid crystal E7 and alignment material AtA-2 (round & triangular dots) 11 material, implementing new photoalignment mechanism, has been successfully applied for creation of various photonic devices. [17][18][19] Moreover, according to Equation 6, azimuthal anchoring energy coefficient depends on the square of the dipole moment of the alignment material (μ AL ) 2 . Thus, we consider the possibility of chemical modification of the AtA-2 azo-dye structure (Figure 4) with the aim to increase the dipole moment of the dye molecule concluding with the AtA-0042 azo-dye structure (Figure 8).…”

Section: Results Analysis and Application For High Anchoring Photoalignment Materialsmentioning

confidence: 99%

High anchoring photoalignment material based on new photo‐induced hole dipoles' mechanism

et al. 2021

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Flat nonprofiled surface of photoalignment AtA-2 azo-dye layer possesses simultaneously low molecular orientation anisotropy and strong azimuthal anchoring energy. We explain how flat surface of alignment layer orients nematic liquid crystal and show the existence of the new photoalignment mechanism based on photo-induced hole dipole moments in the azo-dye layer. The dependence of anchoring energy coefficient on the square of dipole moments of the alignment layer and the liquid crystal layer is formulated, grounding the idea of chemical modification of AtA-2 azo-dye with molecular dipole moment $16D to obtain novel high anchoring photoalignment material. The new AtA-0042 azo-dye with molecular dipole moment $27.5D is synthesized and experimentally verified. Strong azimuthal anchoring energy over >1.4 Â 10 À4 J/m 2 is obtained for AtA-0042 photoalignment material layer with $40 mJ/cm 2 exposure dose.

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Electrically switchable photonic liquid crystal devices for routing of a polarized light wave

Cited by 23 publications

References 15 publications

Electro-Steering Tapered Fiber-Optic Device with Liquid Crystal Cladding

Electro-Steering Tapered Fiber-Optic Device with Liquid Crystal Cladding

Alignment Control of Nematic Liquid Crystal using Gold Nanoparticles Grafted by the Liquid Crystalline Polymer with Azobenzene Mesogens as the Side Chains

High anchoring photoalignment material based on new photo‐induced hole dipoles' mechanism

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