scholarly journals Optical properties of metasurfaces infiltrated with liquid crystals

2020 ◽  
Vol 117 (34) ◽  
pp. 20390-20396 ◽  
Author(s):  
Andrew Lininger ◽  
Alexander Y. Zhu ◽  
Joon-Suh Park ◽  
Giovanna Palermo ◽  
Sharmistha Chatterjee ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Design ◽  
Dynamic Control ◽  
Fdtd Simulation ◽  
Optical Elements ◽  
Difference Time ◽  
Local Refractive Index

Optical metasurfaces allow the ability to precisely manipulate the wavefront of light, creating many interesting and exotic optical phenomena. However, they generally lack dynamic control over their optical properties and are limited to passive optical elements. In this work, we report the nontrivial infiltration of nanostructured metalenses with three respective nematic liquid crystals of different refractive index and birefringence. The optical properties of the metalens are evaluated after liquid-crystal infiltration to quantify its effect on the intended optical design. We observe a significant modification of the metalens focus after infiltration for each liquid crystal. These optical changes result from modification of local refractive index surrounding the metalens structure after infiltration. We report qualitative agreement of the optical experiments with finite-difference time-domain solver (FDTD) simulation results. By harnessing the tunability inherent in the orientation dependent refractive index of the infiltrated liquid crystal, the metalens system considered here has the potential to enable dynamic reconfigurability in metasurfaces.

Infrared Microscopic Imaging of the Diffusion of Liquid Crystals into Thermoplastics

1997 ◽  
Vol 3 (S2) ◽  
pp. 841-842
Author(s):  
Bentley G. Wall ◽  
Chris M. Snively ◽  
Jack L. Koenig
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Field ◽  
Polymer Matrix ◽  
Thermoplastic Polymer ◽  
General Direction ◽  
Display Devices ◽  
Polymer Dispersed

Thermoplastic polymer/liquid crystal systems have found application in the generation of display devices known as thermoplastic, polymer dispersed liquid crystals (PDLCs). These systems take advantage of the beneficial properties of both components to generate a device that has unique optical properties. The liquid crystal is dielectric and responds to an electric field. The polymer confines the liquid crystal so that the cells are closed. The two components are melted together until they are miscible. At lower temperatures, the two components phase separate. The liquid crystal component is the minor phase and takes the form of many tiny droplets contained within the major-phase, polymer matrix. An application of an electric field across these systems causes the liquid crystal within the droplets to align with the field. The systems are engineered such that when this alignment occurs there is no refractive index difference between the liquid crystal in the droplets and the polymer matrix, thus, the cells appear optically transparent. When there is no field applied, the liquid crystals in each droplet are aligned without respect to a general direction according to the surface energetics of each droplet/polymer interface. When this is the case, there is a refractive index mismatch between the droplets and the polymer and the cells are opaque. Research of these systems is aimed at improving the optical properties in order to facilitate the manufacturing of improved devices utilizing this technology. Because these systems are generated by a diffusion-controlled, phase separation process, understanding the relevant parameters, particularly the diffusion coefficients, should enable the manufacturing processes of these systems to be controlled more efficiently, generating improved optical properties.

Optical properties of a liquid crystal with small ordinary and extraordinary refractive indices and small optical anisotropy

2014 ◽  
Vol 22 (3) ◽  
Author(s):  
J. Kędzierski ◽  
K. Garbat ◽  
Z. Raszewski ◽  
M. Kojdecki ◽  
K. Kowiorski ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Optical Anisotropy ◽  
Order Parameter ◽  
Orientational Order ◽  
Refractive Indices ◽  
Orientational Order Parameter ◽  
Unknown Density ◽  
Abbe Refractometer

AbstractOptical properties of a nematic liquid crystal with small refractive index and small birefringence were studied. The ordinary and extraordinary refractive indices and birefringence were measured as functions of temperature by using an Abbe refractometer and wedge nematic cells. From values of these indices the nematic orientational order parameter was calculated by using several methods and corresponding mathematical models. Kuczyński et al. method was found to be suitable for determining the order parameter also for materials featuring small ordinary refractive index, with unknown density.

scholarly journals Optical Properties of Electrically Active Gold Nanoisland Films Enabled with Interfaced Liquid Crystals

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 290 ◽  
Author(s):  
Hung-Chi Yen ◽  
Tsung-Rong Kuo ◽  
Chun-Ta Wang ◽  
Jia-De Lin ◽  
Chia-Chun Chen ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Active Control ◽  
Resonance Wavelength ◽  
Hybrid Structure ◽  
Optical Devices ◽  
Nanostructured Surface ◽  
Wavelength Tunability ◽  
Nanoisland Film

A system comprising a gold nanoisland film (Au NIF) covered with a liquid crystal (LC) material is introduced. By applying a voltage across the LC bulk, we demonstrate that changes in the refractive-index and orientation significantly modified the hybrid plasmonic–photonic resonances of the Au NIF. The hybrid structure enabled active control of the spectrum of the resonance wavelength of the metallic nanoisland by means of an externally applied electric field. Our modeling supports the observed results in LC/Au NIF. In a combination of the nanostructured surface with birefringent LCs, nonpolarized wavelength tunability of ~15 nm and absorbance tunability of ~0.024 were achieved in the visible wavelength, opening the door to optical devices and nanoscale sensors.

Optically Controlled Light Propagation in Dye-Doped Nematic Liquid Crystals with Homogeneous Alignment

2011 ◽  
Vol 497 ◽  
pp. 142-146
Author(s):  
Tomoyuki Sasaki ◽  
Kenta Miura ◽  
Hiroshi Ono ◽  
Osamu Hanaizumi
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Absorption Band ◽  
Temperature Variation ◽  
Light Propagation ◽  
Light Signal ◽  
Photothermal Effect ◽  
Absorption Of Light ◽  
Control Light

Light propagation in an optical waveguide fabricated by employing a dye-doped liquid crystal (DDLC) was observed. The propagation of a light signal in the waveguide was varied by irradiation with a control light whose wavelength was in the absorption band of the DDLC. By considering the photothermal effect of the DDLC, which enables the change of the refractive index due to temperature variation based on the absorption of light, we qualitatively explained the observed light propagation and demonstrated manipulation of the propagation.

Active Photonic Crystals Based multiplexer

2006 ◽  
Vol 934 ◽  
Author(s):  
Principia Dardano ◽  
Vito Mocella ◽  
Luigi Sirleto ◽  
Luigi Moretti ◽  
Ivo Rendina
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Photonic Crystal ◽  
Photonic Crystals ◽  
Square Lattice ◽  
Two Dimensional ◽  
Optical Effect ◽  
Electro Optical Effect ◽  
Silicon Rods

ABSTRACTIn the last years, in order to achieve active tuning of photonic crystals devices, the possibility to use liquid crystal inside photonic crystals has been explored.On this line of argument, in this paper, we numerically investigate a tunable T-shaped waveguide diplexer, based on a two-dimensional square lattice photonic crystal composed of silicon rods in a liquid crystals. We prove that complete splitting of the entire input wavelengths range in two sub-ranges symmetrical with respect to the middle (switching) wavelength, and propagating in right and left arms respectively, can be achieved. Moreover, changing the refractive index of liquid crystals by electro-optical effect, a tuning of switching wavelength of about 60 nm can be obtained.

Textural Spectral Characteristics of the Cholesteric Liquid Crystal

2010 ◽  
Vol 428-429 ◽  
pp. 241-246
Author(s):  
Jia Ling Wang ◽  
Xin Du ◽  
Jia Lv ◽  
Tian Chi Yu ◽  
Zhi Xin Fan
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Cholesteric Liquid Crystal ◽  
Spectral Characteristics ◽  
Optoelectronic Devices ◽  
Liquid Crystal Displays ◽  
Transmission Property ◽  
Large Crystal ◽  
Important Significance

For the cholesteric liquid crystal (hereinafter short for Ch-LC) possesses special optical properties, it has specific applications in the area of liquid crystal displays and optoelectronic devices. Specimens of Ch-LCs in planar and focal conic texture stably are prepared. The photographs of textures are shot by polarizing microscope and transmittance spectrums of different textures are measured by spectrophotometer. It is found that the specimen in focal conic texture with large crystal domains has the well transmission property. The experiment has an important significance for applications of liquid crystals.

Collective and Individual Molecular Nonlinear Photonics of Liquid Crystals

2003 ◽  
Vol 12 (02) ◽  
pp. 277-289 ◽  
Author(s):  
I. C. Khoo ◽  
Andres Diaz ◽  
J. Ding ◽  
K. Chen ◽  
Y. Zhang
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystals ◽  
Isotropic Phase ◽  
Optical Elements ◽  
Fiber Arrays ◽  
Nonlinear Responses ◽  
Upper Limit ◽  
Phase Liquid ◽  
Nonlinear Light Scattering

This review will examine the origins of nonlinear light scattering processes in nematic liquid crystals, and explore various nonlinear photonic processes associated with optically induced director axis reorientation effects. Our theoretical prediction shows that the upper limit of nematic liquid crystal reorientation nonlinearity can be as high as 1000 cm2/W. The supra-nonlinear responses of nematic liquid crystals enable various self-action or electro-optical guiding, mixing, switching and modulation of light with unprecedented low power thresholds. Owing to the broadband birefringence of NLC, we expect to realize optical elements/devices capable of similar multi-functional operations throughout the visible — infrared regime. We also discuss the optical limiting action of isotropic-phase liquid crystal filled nonlinear fiber arrays.

scholarly journals Photo-Aligned Ferroelectric Liquid Crystal Devices with Novel Electro-Optic Characteristics

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 563
Author(s):  
Vladimir Chigrinov ◽  
Qi Guo ◽  
Aleksey Kudreyko
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Berry Phase ◽  
Photonic Devices ◽  
Ferroelectric Liquid Crystal ◽  
Optical Elements ◽  
Ferroelectric Liquid Crystals ◽  
Liquid Crystal Devices ◽  
Alignment Technique ◽  
Photo Alignment

This paper examines different applications of ferroelectric liquid crystal devices based on photo-alignment. Successful application of the photo-alignment technique is considered to be a critical breakthrough. A variety of display and photonic devices with azo dye aligned ferroelectric liquid crystals is presented: smart glasses, liquid crystal Pancharatnam–Berry phase optical elements, 2D/3D switchable lenses, and laser therapy devices. Comparison of electro-optical behavior of ferroelectric liquid crystals is described considering the performance of devices. This paper facilitates the optimization of device design, and broadens the possible applications in the display and photonic area.

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