Photorefractive chiral smectic <i>A</i> phases

Termine, Roberto; Simone, Bruna Clara De; Golemme, Attilio

doi:10.1063/1.1345824

Cited by 17 publications

(8 citation statements)

References 14 publications

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“…[168] The photorefractive effect, which consists of electric field induced space-modulation of the refractive index due to the presence of photogenerated charges, was created by using a layer of a photoconductive material (PVK) coated at both substrates of a slab cell. [168] The photorefractive effect, which consists of electric field induced space-modulation of the refractive index due to the presence of photogenerated charges, was created by using a layer of a photoconductive material (PVK) coated at both substrates of a slab cell.…”

Section: Smetic a Chiral Smectic A And Smectic C Lcsmentioning

confidence: 99%

“…Chiral SmA phase has been used to fabricate gratings by using photorefractive effect. [168] The photorefractive effect, which consists of electric field induced space-modulation of the refractive index due to the presence of photogenerated charges, was created by using a layer of a photoconductive material (PVK) coated at both substrates of a slab cell. The SmA* LC was injected into the cell and two laser beams were superimposed on the sample, thus creating charge separation on the interfering beams.…”

Section: Smetic a Chiral Smectic A And Smectic C Lcsmentioning

confidence: 99%

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Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

et al. 2018

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the duality consolidation, the idea of controlling light and how it interacts with matter has always been an exciting topic. Visible light, as we perceive it, is a small portion of the electromagnetic spectrum composed of mutually perpendicular oscillating electric and magnetic fields that propagate through space and presents wave-like and particle-like behavior. Since the elements comprising matter possess dynamic electron clouds, the electromagnetic nature of light prompts different responses when it interacts with different materials, depending on its intensity, frequency, the arrangement of molecules, and so on. Whenever light interacts with matter, it might be absorbed, re-emitted, scattered, or transmitted. Although these effects are well known, the combination of them with new, innovative materials pushes optics forward. In fact, advances in optics have often occurred through the development of materials with improved optical properties, thus creating remarkable applications that tremendously influence our daily lives. These exciting applications include image processing and recording, lasing, data storage, display devices, detector systems, propulsion systems, and optical tweezers, which have enabled remote micromanipulation of colloidal particles and promising applications in various biomedical and biological applications. [1][2][3] There is, however, one component that stands out: the diffraction grating. It is generally regarded as one of the most important devices in the development of several fields of science. [4] Such importance comes from the fact that a diffraction grating is a device with a periodic structure capable of changing the propagation and splitting the spectrum The ability to control light direction with tailored precision via facile means is long-desired in science and industry. With the advances in optics, a periodic structure called diffraction grating gains prominence and renders a more flexible control over light propagation when compared to prisms. Today, diffraction gratings are common components in wavelength division multiplexing devices, monochromators, lasers, spectrometers, media storage, beam steering, and many other applications. Next-generation optical devices, however, demand nonmechanical, full and remote control, besides generating higher than 1D diffraction patterns with as few optical elements as possible. Liquid crystals (LCs) are great candidates for light control since they can form various patterns under different stimuli, including periodic structures capable of behaving as diffraction gratings. The characteristics of such gratings depend on several physical properties of the LCs such as film thickness, periodicity, and molecular orientation, all resulting from the internal constraints of the sample, and all of these are easily controllable. In this review, the authors summarize the research and development on stimuli-controllable diffraction gratings and beam steering using LCs as the active optical materials. Dynamic gratings fabricated by applying external f...

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Section: Smetic a Chiral Smectic A And Smectic C Lcsmentioning

confidence: 99%

Section: Smetic a Chiral Smectic A And Smectic C Lcsmentioning

confidence: 99%

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

et al. 2018

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“…The first photorefractive liquid crystals were nematic mesophases [5][6][7][8][9], where the director reorientation is due to dielectric anisotropy. More recently, the first studies of photorefractive smectic mesophase have also appeared [10][11][12]. While in nematics the reorientation is an effect which is quadratic in the electric field, in smectics it is linear.…”

Section: Introductionmentioning

confidence: 97%

Space-Charge Field Induced Refractive Index Modulation in Chiral Smectic A and C Mesophases: A Simple Model

Termine

Golemme

2003

Molecular Crystals and Liquid Crystals

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The photorefractive properties of chiral smectic A and C phases were studied using a model we had previously developed. The space-charge field induced reorientations considered are due to the electroclinic effect, in the case of the chiral smectic A, and to the reorientation of the spontaneous polarization for the chiral smectic C. The model takes into account both geometrical parameters, like for example light direction and polarization, and material parameters, like birefringence, spontaneous tilt angle or electroclinic coefficient. Results are extremely useful in order to optimize material parameters.

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“…Photorefractivity in liquid crystals was first observed in nematics [6,7], but more recently photorefractivity in bulk SmC Ã phases [8] and bulk [9] and dispersed SmA Ã [10] phases has also been reported. Liquid crystals are extremely appealing for photorefractivity because they exhibit several orientational mechanisms through which the space charge field can modulate the refractive index.…”

Section: Introductionmentioning

confidence: 98%

Bistable Switching in Photorefractive Surface Stabilized Ferroelectric Liquid Crystals

Talarico¹,

Golemme²

2007

Molecular Crystals and Liquid Crystals

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By using a photogenerated space-charge field to reorient the spontaneous polarization, we report an approach towards the optical control of switching in a surface stabilized ferroelectric liquid crystal that exhibits two stable orientational states. The space-charge field was generated on the surfaces of the SSFLC device, by sandwiching the FLC between two photoconducting layers, or within its bulk by doping. In the second case, we observed the formation of a grating, stable at least for months, which can be easily erased and rewritten. Experiments have been done to probe its photorefractive nature.

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Photorefractive chiral smectic A phases

Abstract: Diffraction efficiency and phase stability of poly (N-vinylcarbazole) -based photorefractive polymer composites as a function of azo-dye concentration

Cited by 17 publications

References 14 publications

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

Space-Charge Field Induced Refractive Index Modulation in Chiral Smectic A and C Mesophases: A Simple Model

Bistable Switching in Photorefractive Surface Stabilized Ferroelectric Liquid Crystals

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