Optical vortex generation in homeotropic NLCs in the presence of DC electric field

Shvetsov, S. A.; Zolot’ko, A. S.

doi:10.1080/15421406.2016.1198663

Cited by 7 publications

(6 citation statements)

References 12 publications

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“…Therefore, this option has the potential for being simultaneously pure and efficient 21 , despite reported record efficiencies of the order of ∼ 30%. 22 Here, we revisit previous attempts 15,22 and we experimentally demonstrate that highly efficient (> 90%) self-induced spin-orbit optical vortex generation can be achieved.…”

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confidence: 74%

Self-induced liquid crystal q-plate by photoelectric interface activation

Kravets

Podoliak

Kaczmarek

et al. 2019

Applied Physics Letters

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Here we report on the experimental demonstration that highly efficient self-induced spin-orbit optical vortex generation can be achieved by using standard liquid crystal materials and surface treatment agents. This is done by revisiting recent attempt by Zolot'ko and coworkers to produce self-induced liquid crystal vortex plates using dc electric field [Mol. Cryst. Liq. Cryst. 637, 47 (2016)] that remains, so far, limited to moderate efficiencies. The phenomenon is the result of the self-back-action of light arising from the spontaneous creation of a liquid crystal topological defect. These results demonstrate photo-electric interface activation as a candidate towards the development of a self-adapted spin-orbit photonic toolbox, thus enabling agile management of the orbital angular momentum of light.

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confidence: 74%

Self-induced liquid crystal q-plate by photoelectric interface activation

Kravets

Podoliak

Kaczmarek

et al. 2019

Applied Physics Letters

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“…Electric field in the illuminated NLC cell by a light beam at normal incident to the surfaces can have a fringe profile in the planar configuration as a result of the SPR effect. The induced fringe electric field inside the LC volume is capable of realigning NLCs (with positive and negative dielectric anisotropies) from initial homeotropic alignment when shone by a low laser power (of a few mW) at a reduced threshold voltage [74][75][76][77], as schematically shown in Figure 4. Independent of the sign of the dielectric anisotropy, radial director field distributions in the transverse plane were seen as a result of director realignments from initial homeotropic alignment induced by the SPR effect [74][75][76][77].…”

Section: Generation Of Optical Vortices In the Nlc Context Due To The Spr Effectmentioning

confidence: 99%

“…The induced fringe electric field inside the LC volume is capable of realigning NLCs (with positive and negative dielectric anisotropies) from initial homeotropic alignment when shone by a low laser power (of a few mW) at a reduced threshold voltage [74][75][76][77], as schematically shown in Figure 4. Independent of the sign of the dielectric anisotropy, radial director field distributions in the transverse plane were seen as a result of director realignments from initial homeotropic alignment induced by the SPR effect [74][75][76][77]. This leads to the formation of optical vortices (OVs) [78][79][80] from an incident plane wave.…”

Section: Generation Of Optical Vortices In the Nlc Context Due To The Spr Effectmentioning

confidence: 99%

“…Since this mechanism is more effective at the anode electrode connected to the positive polarity of the DC voltage (verified from the elongation direction of the aberrational patterns [61]), the modeling of the induced electric field was roughly simplified here by assuming only one positive point charge located near the anode at a distances l A relative to the cell midplane. It represents the redistributed surface electric charges at the corresponding electrode [74][75][76]. The simplified model was able to describe the generation of OVs in the corresponding test cells well [74][75][76].…”

Section: Generation Of Optical Vortices In the Nlc Context Due To The Spr Effectmentioning

confidence: 99%

“…It represents the redistributed surface electric charges at the corresponding electrode [74][75][76]. The simplified model was able to describe the generation of OVs in the corresponding test cells well [74][75][76].…”

Section: Generation Of Optical Vortices In the Nlc Context Due To The Spr Effectmentioning

confidence: 99%

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Photorefractive Effect in NLC Cells Caused by Anomalous Electrical Properties of ITO Electrodes

Habibpourmoghadam

2020

Crystals

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In a pure nematic liquid crystal (NLC) cell, optically induced charge carriers followed by transports in double border interfaces of orientant/LC and indium-tin-oxide (ITO)/orientant (or LC) can cause removal of screening of the static electric field inside the LC film. This is called surface photorefractive effect (SPR), which induces director field reorientation at a low DC electric field beyond the threshold at a reduced Fréedericksz transition and, as a result, a modulation of the LC effective refractive index. The studies conducted on the photoinduced opto-electrical responses in pure nematic LC cells biased with uniform static DC electric fields support the SPR effect (attributed to the photoelectric activation of the double interfaces). The SPR effect was further studied in LC cells with photoresponsive substrates, which act as a source of a bell-shaped electric field distribution in the LC film if no ITO electrode was employed. In an equipped cell with ITO, the photovoltaic electric field induces charge carrier redistribution in the ITO film, hence the SPR effect. This paper is aimed at highlighting all the evidences supporting ITO film as one of the fundamental sources of the SPR effect in pure NLC cells under the condition of applying low optical power and low DC voltage. An optically induced fringe electric field stemming from inhomogeneous photo-charge profiles near the electrode surfaces is expected in the LC film due to the semiconducting behavior of the ITO layer.

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Singular Optics of Liquid Crystal Defects

Brasselet¹

2021

Liquid Crystals

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Optical vortex generation in homeotropic NLCs in the presence of DC electric field

Cited by 7 publications

References 12 publications

Self-induced liquid crystal q-plate by photoelectric interface activation

Self-induced liquid crystal q-plate by photoelectric interface activation

Photorefractive Effect in NLC Cells Caused by Anomalous Electrical Properties of ITO Electrodes

Singular Optics of Liquid Crystal Defects

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