scholarly journals Liquid Crystal Devices for Beam Steering Applications

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 247
Author(s):  
Rowan Morris ◽  
Cliff Jones ◽  
Mamatha Nagaraj
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Adaptive Optics ◽  
Beam Steering ◽  
Optical Components ◽  
Advantages And Disadvantages ◽  
Liquid Crystal Devices

Liquid crystals are valuable materials for applications in beam steering devices. In this paper, an overview of the use of liquid crystals in the field of adaptive optics specifically for beam steering and lensing devices is presented. The paper introduces the properties of liquid crystals that have made them useful in this field followed by a more detailed discussion of specific liquid crystal devices that act as switchable optical components of refractive and diffractive types. The relative advantages and disadvantages of the different devices and techniques are summarised.

scholarly journals Overlooked Ionic Phenomena Affecting the Electrical Conductivity of Liquid Crystals

2021 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
David Webb ◽  
Yuriy Garbovskiy
Keyword(s):  
Electrical Conductivity ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Physical Properties ◽  
Soft Matter ◽  
Photonic Devices ◽  
Optical Components ◽  
Dynamically Reconfigurable ◽  
Liquid Crystal Devices ◽  
New Applications

Liquid crystal devices, such as displays, various tunable optical components, and sensors, are becoming increasingly ubiquitous. Basic physical properties of liquid crystal materials can be controlled by external physical fields, thus making liquid crystal devices dynamically reconfigurable. The tunability of liquid crystals offers exciting opportunities for the development of new applications, including advanced electronic and photonic devices, by merging the concepts of flat optics, tunable metasurfaces, nanoplasmonics, and soft matter biophotonics. As a rule, the tunability of liquid crystals is achieved by applying an electric field. This field reorients liquid crystals and changes their physical properties. Ions, typically present in liquid crystals in minute quantities, can alter the reorientation of liquid crystals through the well-known screening effect. Because the electrical conductivity of thermotropic liquid crystals is normally caused by ions, an understanding of ion generation processes in liquid crystals is of utmost importance to existing and emerging technologies relying on such materials. That is why measuring of electrical conductivity of liquid crystals is a standard part of their material characterization. Measuring the electrical conductivity of liquid crystals is a very delicate process. In this paper, we discuss overlooked ionic phenomena caused by interactions of ions with substrates of the liquid crystal cells. These interactions affect the measured values of the DC electrical conductivity of liquid crystals and make them dependent on the cell thickness.

Smart Glass and Its Potential in Energy Savings

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Kaufui V. Wong ◽  
Richard Chan
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Energy Demand ◽  
Energy Savings ◽  
Suspended Particle ◽  
Light Transmittance ◽  
Voltage Source ◽  
Glass Technology ◽  
Ion Conductor ◽  
Advantages And Disadvantages

Smart glass is such that its properties may be changed by application of a potential across it. The change in properties may be engineered to alter the amount of heat energy that can penetrate the glass which provides heating and cooling design options. Therein lies its potential in energy savings. Smart glass may be classified into three types: electrochromic, suspended particle, and polymer dispersed liquid crystal (PDLC). Each of these types has their own mechanisms, advantages, and disadvantages. Electrochromic smart glass is the most popular, currently it utilizes an electrochromic film with an ion storage layer and ion conductor placed between two transparent plates. The electrochromic film is usually made of tungsten oxide, owing to the electrochromic nature of transition metals. An electric potential initiates a redox reaction of the electrochromic film transitioning the color and the transparency of the smart glass. Suspended particle smart glass has needle shaped particles suspended within an organic gel placed between two electrodes. In its off state, the particles are randomly dispersed and have a low light transmittance. Once a voltage is applied, the needle particles will orient themselves to allow for light to pass through. PDLC smart glass works similarly to the suspended particle variety. However, in PDLC smart glass, the central layer is a liquid crystal placed within a polymer matrix between electrodes. Similar in behavior to the suspended particles, in the off position the liquid crystals are randomly dispersed and have low transmittance. With the application of a voltage, the liquid crystals orient themselves, thereby allowing for the transmittance of light. These different smart glasses have many different applications, but with one hindrance. The requirement of a voltage source is a major disadvantage which greatly complicates the overall installation and manufacturing processes. However, the integration of photovoltaic (PV) devices into smart glass technology has provided one solution. Photovoltaic films attached in the smart glass will provide the necessary voltage source. The photovoltaic film may even be designed to produce more voltage than needed. The use a photovoltaic smart glass system provides significant cost savings in regards to heating, cooling, lighting, and overall energy bills. Smart glass represents a technology with a great deal of potential to reduce energy demand. Action steps have been identified to propagate the popular use of smart glass.

scholarly journals Theoretical approach of a polymer stabilized blue phase beam steering

2017 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Jose Francisco Algorri ◽  
Virginia Urruchi ◽  
Noureddine Bennis ◽  
Jose Manuel Sanchez-Pena
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Response Time ◽  
Deflection Angle ◽  
Beam Steering ◽  
Phase Plate ◽  
First Case ◽  
Phase Liquid ◽  
Blue Phase ◽  
Polymer Stabilized

Nematic liquid crystal (LC)-based beam steering has been reported for wide applications. However, for conventional nematic LC beam steering the thickness is of several microns in order to have a wider deflection angle. The response time is relatively slow and the diffraction efficiency is low. In this work, novel beam steering based on polymer stabilized blue phase liquid crystal (PS-BPLC) has been designed and theoretically analyzed. This special mesophase of the chiral doped nematic LC has several advantageous characteristics, for example no need for alignment layers, microsecond response time and an isotropic voltage-off state. The results reveal control over phase retardation. The direction of the steered beam can be tuned by voltage. Depending on voltage configuration, either diffractive beam steering (0.5deg deviation for 1st order) or a tunable continuous phase (tunable deviation of 0.002deg) can be obtained. In the first case, the deflection angle could be tuned by stacks of samples. The second option has the same phase shift for the TE and TM modes so unpolarized light could be used. Full Text: PDF ReferencesF. Feng, I. White, T. Wilkinson, "Free Space Communications With Beam Steering a Two-Electrode Tapered Laser Diode Using Liquid-Crystal SLM", J. Lightwave Technol. 31, 2001 (2013). CrossRef E. Oton, J. Perez-Fernandez, D. Lopez-Molina, X. Quintana, J.M. Oton, M.A. Geday, "Reliability of Liquid Crystals in Space Photonics", IEEE Photonics Journal 7, 1 (2015). CrossRef J. Stockley, S. Serati, "Multi-access laser terminal using liquid crystal beam steering", IEEE in Aerospace Conference, 1972 (2005). CrossRef D. Zografopoulos and E. Kriezis, "Switchable beam steering with zenithal bistable liquid-crystal blazed gratings", Opt. Lett. 39, 5842 (2014). CrossRef Benedikt Scherger, et al., "Discrete Terahertz Beam Steering with an Electrically Controlled Liquid Crystal Device", J. Infrared. Millim. Terahertz Waves 33, 1117 (2012). CrossRef M.A. Geday, X. Quintana, E. Otón, B. Cerrolaza, D. Lopez, F. Garcia de Quiro, I. Manolis, A. Short, Proc. ICSO, Rhodes, Greece, pp. 1-4 (2010). CrossRef Y. Chen, S.-T. Wu, "The outlook for blue-phase LCDs", Proc. SPIE 9005, Advances in Display Technologies IV, 900508 (2014). CrossRef G.D. Love, A.F. Naumov, "Modal liquid crystal lenses", Liq. Cryst. Today 10, 1 (2000). CrossRef V. Urruchi, J.F. Algorri, J.M. Sánchez-Pena, M.A. Geday, X. Quintana, N. Bennis, "Lenticular Arrays Based on Liquid Crystals", Opto-Electron. Rev. 20, 38 (2012). CrossRef J.F. Algorri, G. Love, and V. Urruchi, "Modal liquid crystal array of optical elements", Opt. Express 21, 24809 (2013). CrossRef J.F. Algorri, V. Urruchi, N. Bennis, J. Sánchez-Pena, "Modal liquid crystal microaxicon array", Opt. Lett. 39, 3476 (2014). CrossRef J.F. Algorri, V. Urruchi, B. Garcia-Camara, J.M. Sánchez-Pena, "Generation of Optical Vortices by an Ideal Liquid Crystal Spiral Phase Plate", IEEE Elect. Dev. Lett. 35, 856 (2014). CrossRef D. Xu, Y. Chen, Y. Liu, S. Wu, "Refraction effect in an in-plane-switching blue phase liquid crystal cell", Opt. Express 21, 24721 (2013). CrossRef Z. Ge, S. Gauza, M. Jiao, H. Xianyu, S.T. Wu, "Electro-optics of polymer-stabilized blue phase liquid crystal displays", Appl. Phys. Lett. 94 101104 (2009). CrossRef J. Yan et al., "Extended Kerr effect of polymer-stabilized blue-phase liquid crystals", Appl. Phys. Lett. 96, 071105 (2010). CrossRef X. Wang, D. Wilson, R. Muller, P. Maker, D. Psaltis, "Liquid-crystal blazed-grating beam deflector, Appl. Opt. 39, 6545 (2000). CrossRef

scholarly journals Carbon Allotropes as ITO Electrode Replacement Materials in Liquid Crystal Devices

2020 ◽  
Vol 6 (4) ◽  
pp. 80
Author(s):  
Ingo Dierking
Keyword(s):  
Liquid Crystal ◽  
Indium Tin Oxide ◽  
Electrode Materials ◽  
Mobile Technologies ◽  
Scale Production ◽  
Advantages And Disadvantages ◽  
Liquid Crystal Devices ◽  
The Future ◽  
Technical Specifications ◽  
Carbon Based

Indium tin oxide (ITO)-free optoelectronic devices have been discussed for a number of years in the light of a possible indium shortage as demand rises. In particular, this is due to the largely increased number of flat panel displays and especially liquid crystal displays (LCDs) being produced for home entertainment TV and mobile technologies. While a shortage of primary indium seems far on the horizon, nevertheless, recycling has become an important issue, as has the development of ITO-free electrode materials, especially for flexible liquid crystal devices. The main contenders for new electrode technologies are discussed with an emphasis placed on carbon-based materials for LCDs, including composite approaches. At present, these already fulfil the technical specifications demanded from ITO with respect to transmittance and sheet resistance, albeit not in relation to cost and large-scale production. Advantages and disadvantages of ITO-free technologies are discussed, with application examples given. An outlook into the future suggests no immediate transition to carbon-based electrodes in the area of LCDs, while this may change in the future once flexible displays and environmentally friendly smart window solutions or energy harvesting building coverings become available.

scholarly journals Ion-Generating and Ion-Capturing Nanomaterials in Liquid Crystals

Proceedings ◽  
2018 ◽  
Vol 2 (14) ◽  
pp. 1122
Author(s):  
Yuriy Garbovskiy
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Fields ◽  
Future Research ◽  
Research Directions ◽  
Liquid Crystal Devices ◽  
Proposed Model ◽  
Future Research Directions ◽  
Practical Implications ◽  
Good Agreement

The majority of tunable liquid crystal devices are driven by electric fields. The performance of such devices can be altered by the presence of small amounts of ions in liquid crystals. Therefore, the understanding of possible sources of ions in liquid crystal materials is very critical to a broad range of existing and future applications employing liquid crystals. Recently, nanomaterials in liquid crystals have emerged as a hot research topic, promising for its implementation in the design of wearable and tunable liquid crystal devices. An analysis of published results revealed that nanodopants in liquid crystals can act as either ion-capturing agents or ion-generating objects. In this presentation, a recently developed model of contaminated nanomaterials is analyzed. Nanoparticle-enabled ion capturing and ion generation regimes in liquid crystals are discussed within the framework of the proposed model. This model is in very good agreement with existing experimental results. Practical implications and future research directions are also discussed.

Adaptive optics using MEMS and liquid crystal devices

2008 ◽  
Vol 10 (6) ◽  
pp. 064006 ◽  
Author(s):  
S R Restaino ◽  
J R Andrews ◽  
T Martinez ◽  
F Santiago ◽  
D V Wick ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Adaptive Optics ◽  
Liquid Crystal Devices

New liquid crystal devices for adaptive optics

2002 ◽  
Author(s):  
Sergio R. Restaino ◽  
Jeffrey T. Baker ◽  
Don M. Payne
Keyword(s):  
Liquid Crystal ◽  
Adaptive Optics ◽  
Liquid Crystal Devices

scholarly journals Spontaneous helielectric nematic liquid crystals: Electric analog to helimagnets

2021 ◽  
Vol 118 (42) ◽  
pp. e2111101118
Author(s):  
Xiuhu Zhao ◽  
Junchen Zhou ◽  
Jinxing Li ◽  
Junichi Kougo ◽  
Zhe Wan ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nonlinear Optical ◽  
Room Temperature ◽  
Nematic Liquid Crystals ◽  
Polar Liquid ◽  
Experimental Proof ◽  
Liquid Crystal Devices ◽  
Optical Responses ◽  
Electric Analog

Recently, a type of ferroelectric nematic fluid has been discovered in liquid crystals in which the molecular polar nature at molecule level is amplified to macroscopic scales through a ferroelectric packing of rod-shaped molecules. Here, we report on the experimental proof of a polar chiral liquid matter state, dubbed helielectric nematic, stabilized by the local polar ordering coupled to the chiral helicity. This helielectric structure carries the polar vector rotating helically, analogous to the magnetic counterpart of helimagnet. The helielectric state can be retained down to room temperature and demonstrates gigantic dielectric and nonlinear optical responses. This matter state opens a new chapter for developing the diverse polar liquid crystal devices.

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