Liquid crystal bubbles forming a tunable micro-lenses array

Hamdi, Ridha; Petriashvili, Gia; Lombardo, Giuseppe; Santo, Maria P. De; Barberi, R.

doi:10.1063/1.3642972

Cited by 17 publications

(12 citation statements)

References 31 publications

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“…The optical images of the generated axisymmetric structure resemble those taken for bubble domain [6] or toron [19]. The observed light diffraction pattern (Figure 2a) is also similar to the patterns, obtained upon light propagation through a cholesteric bubble [14,39,40]. Based on this, we believe that thermo-optically induced domains possess a director field distribution similar to that of bubble domains [13].…”

Section: Discussionsupporting

confidence: 77%

Thermo-Optical Generation of Particle-Like Structures in Frustrated Chiral Nematic Film

et al. 2019

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The creation of metastable particle-like structures in frustrated (unwound) chiral nematic film containing light-absorbing additive is studied. It is shown that such localized structures can be generated by the thermo-optical action of a focused laser beam or arise spontaneously at a phase transition from an isotropic to a liquid crystal state. Observed axisymmetric patterns resemble cholesteric spherulites with toroidal double-twisted director-field configuration.

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Section: Discussionsupporting

confidence: 77%

Thermo-Optical Generation of Particle-Like Structures in Frustrated Chiral Nematic Film

et al. 2019

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“…The BDs show attractive interactions and short‐range repulsive interactions upon weak electric field and without external field, respectively . Such particle‐like behavior and monodisperse size allows their self‐assembly into hexagonally‐packed 2D arrays (Figure b) . In turns, 2D BD arrays can be considered as DGs.…”

Section: Diffraction Structures In Clc Materials Induced By Electric mentioning

confidence: 99%

“…Dependence of focal length on electric field applied. Inset shows 2D array of BDs and its near filed diffraction pattern . a,b) Reproduced with permission .…”

Section: Diffraction Structures In Clc Materials Induced By Electric mentioning

confidence: 99%

Section: Diffraction Structures In Clc Materials Induced By Electric mentioning

confidence: 99%

“…In addition, the domain can act as a microlens. The authors succeeded in adjusting the focal length of such lenses by applying weak DC voltage (for CLCs with Δε < 0), which resulted in increasing the diameter of the BD structure promoting increase in focal length (Figure c) …”

Section: Diffraction Structures In Clc Materials Induced By Electric mentioning

confidence: 99%

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Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

Ryabchun

Bobrovsky

2018

Advanced Optical Materials

186

106

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refractive, diffraction and optical fiber components. In particular, diffraction grating (DG) is one of the key elements for the design and creation of modern optoelectronic devices. One of the most prominent materials for the creation of DGs is liquid crystals. The main feature of these systems is that liquid crystals combine properties such as optical anisotropy inherent for crystals and molecular mobility. High sensitivity to an external field, in particular to an electric field, makes liquid crystals very useful for the creation of DGs with tunable properties. The combination of these properties enables easy control of optical characteristics of such systems and opens wide perspectives for the design of new materials for diffractive optics.Among the different types of liquid crystalline (LC) phases, cholesteric liquid crystal (CLC) phase possesses intrinsic periodicity in the form of the helical supramolecular structure (Figure 1). With the realization of definite alignment conditions, this periodicity has been exploited for generation of DGs. [8,9] Another remarkable feature of the cholesteric mesophase is selective light reflection with the reflection wavelength determined by the simple Equation (1) where n is the average refractive index, and P is the helix pitch. The specific value of helix pitch depends on the chemical structure of the molecules forming the cholesteric phase and concentration of chiral moieties. One of the easiest ways to obtain the cholesteric mesophase is by doping the nematic matrix with chiral components (Figure 1). Variation of structure of chiral molecules by external stimuli leading, for examples, to the photoisomerization, is effectively used for fine tuning of the helix pitch. [10][11][12][13][14][15][16][17] In addition, the application of an electric field also provides a convenient opportunity to change optical properties of the CLC phase. [18][19][20][21] These unique properties enable to design a great variety of optical elements and devices based on CLC layers, films, or cells. Among them it is necessary to mention the media for photo-optical data recording, [22][23][24][25] electrically switchable mirrors, [26,27] optically controllable linearpolarization rotators, [28] coatings with controllable friction and adhesion, [29] materials for display technology, [23,30] secure Modern optics and photonics constantly require break-through materials and designs in order to achieve miniature, lightweight, highly tunable, and effective optical devices. One of the basic optical components is the diffraction grating (DG), widely used for the dispersion of light, beam steering, etc. This review gathers research efforts on diffractive optical elements based on cholesteric liquid crystal (CLC) materials with a supramolecular helical architecture. All main types and fabrication approaches of periodic diffractive structures from CLCs are classified and described. Key optical properties of DGs, their advantages and drawbacks are considered. Special attention is paid on the tunability of DG...

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Singular Optics of Liquid Crystal Defects

Brasselet¹

2021

Liquid Crystals

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Liquid crystal bubbles forming a tunable micro-lenses array

Cited by 17 publications

References 31 publications

Thermo-Optical Generation of Particle-Like Structures in Frustrated Chiral Nematic Film

Thermo-Optical Generation of Particle-Like Structures in Frustrated Chiral Nematic Film

Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

Singular Optics of Liquid Crystal Defects

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