scholarly journals Tunable Polarization Gratings Based on Nematic Liquid Crystal Mixtures Photoaligned with Azo Polymer-Coated Substrates

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 768 ◽  
Author(s):  
Mateusz Nieborek ◽  
Katarzyna Rutkowska ◽  
Tomasz Ryszard Woliński ◽  
Bartosz Bartosewicz ◽  
Bartłomiej Jankiewicz ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Near Infrared ◽  
Beam Steering ◽  
Incident Beam ◽  
Molecular Reorientation ◽  
Electric Voltage ◽  
Azo Polymer ◽  
Order Diffraction ◽  
Polarization Gratings

Liquid crystal polarization gratings are of great interest for optical communications as elements performing beam steering, splitting, multiplexing or beam combining. Material birefringence, cell thickness or a period of the liquid crystal director pattern influence, among other features, spectroscopic and electro-optical characteristics of fabricated devices, determining thus their functionality and applicability. Here, we report on liquid crystal polarization gratings that allow for complete maximization of the first-order diffraction efficiency (resulting in total elimination of the zeroth-order diffraction) for any wavelength of an incident beam from green to the near-infrared spectral region by applying a low electric voltage. The gratings with periods as small as 10 μm were obtained by holographic exposure of the cell substrates coated with light-sensitive azo polymer alignment layers, and then filled with three different liquid crystal mixtures. The influence of gold nanoparticle dopants in the liquid crystalline mixtures on spectroscopic and electro-optical properties of the devices is presented. Moreover, on the basis of the measured transmittance spectra of the fabricated gratings, the unknown birefringence of liquid crystal mixtures as well as their effective birefringence due to molecular reorientation in the electric field in the visible and near IR region were determined.

scholarly journals Design of Tunable Holographic Liquid Crystalline Diffraction Gratings

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6789
Author(s):  
Katarzyna A. Rutkowska ◽  
Anna Kozanecka-Szmigiel
Keyword(s):  
Liquid Crystal ◽  
Communication Networks ◽  
Optical Communication ◽  
Liquid Crystalline ◽  
Incident Light ◽  
Diffraction Gratings ◽  
Lagrange Equations ◽  
Experimental Conditions ◽  
Molecular Distribution ◽  
Polarization Gratings

Tunable diffraction gratings and phase filters are important functional devices in optical communication and sensing systems. Polarization gratings, in particular, capable of redirecting an incident light beam completely into the first diffraction orders may be successfully fabricated in liquid crystalline cells assembled from substrates coated with uniform transparent electrodes and orienting layers that force a specific molecular distribution. In this work, the diffraction properties of liquid crystal (LC) cells characterized by a continually rotating cycloidal director pattern at the cell substrates and in the bulk, are studied theoretically by solving a relevant set of the Euler-Lagrange equations. The electric tunability of the gratings is analyzed by estimating the changes in liquid crystalline molecular distribution and thus in effective birefringence, as a function of external voltage. To the best of our knowledge, such detailed numerical calculations have not been presented so far for liquid crystal polarization gratings showing a cycloidal director pattern. Our theoretical predictions may be easily achieved in experimental conditions when exploiting, for example, photo-orienting material, to induce a permanent LC alignment with high spatial resolution. The proposed design may be for example, used as a tunable passband filter with adjustable bandwidths, thus allowing for potential applications in optical spectroscopy, optical communication networks, remote sensing and beyond.

Beam steering by liquid crystal elastomer fibres

Soft Matter ◽  
2017 ◽  
Vol 13 (45) ◽  
pp. 8590-8596 ◽  
Author(s):  
S. Nocentini ◽  
D. Martella ◽  
D. S. Wiersma ◽  
C. Parmeggiani
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Beam Steering ◽  
Liquid Crystal Elastomer ◽  
Plane Direction

A liquid crystalline elastomer based beam steerer is demonstrated able to address the impinging signal in every in-plane direction.

Beam Pointing Precision Control by Using a Liquid Crystal Optical Phased Array

2010 ◽  
Vol 437 ◽  
pp. 344-348 ◽  
Author(s):  
Li Ying Wu ◽  
Jian Zhang ◽  
Yun Fang
Keyword(s):  
Liquid Crystal ◽  
Phased Array ◽  
Beam Steering ◽  
Incident Beam ◽  
Electric System ◽  
New Device ◽  
Energy Consuming ◽  
Extraordinary Refractive Index ◽  
Optical Phased Array ◽  
Pointing Precision

For laser beam steering, a pure optical-electric system without mechanical or inertial parts is used. The new device is a Liquid Crystal Optical Phased Array (LCOPA). Supplying electric field to liquid crystal cell with electrodes, the extraordinary refractive index changes, which results in phase shift that modulates the direction of incident beam. The advantages of this device are small size, less energy consuming, programmable and addressable control. A one dimensional device is designed and tested. The resolution of the steering angle is 20 μrad, the range is ±2o. The effect of flyback region and phase valley on diffraction efficiency is also discussed briefly.

scholarly journals Diffraction and Polarization Properties of Electrically–Tunable Nematic Liquid Crystal Grating

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1929 ◽  
Author(s):  
Shuan-Yu Huang ◽  
Bing-Yau Huang ◽  
Chi-Chung Kang ◽  
Chie-Tong Kuo
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Electric Fields ◽  
Applied Voltage ◽  
Incident Beam ◽  
Electrode Structure ◽  
First Order ◽  
External Electric Fields ◽  
Order Diffraction ◽  
Liquid Crystal Grating

This work demonstrates an electrically-tunable nematic liquid crystal (NLC) diffraction grating with a periodic electrode structure, and discusses the polarization properties of its diffraction. The efficiency of the first-order diffraction can be gradually controlled by applying external electric fields cross the NLC, and the maximum diffraction efficiency of the first-order diffraction that can be obtained is around 12.5% under the applied voltage of 5.0 V. In addition to the applied electric field, the efficiency of the first-order diffraction can also vary by changing the polarized state of the incident beam. Antisymmetric polarization states with symmetrical intensities in the diffractions corresponding to the +1 and −1 order diffraction signals are also demonstrated.

scholarly journals Tunable light beam steering device using polymer stabilized blue phase liquid crystals

2017 ◽  
Vol 9 (1) ◽  
pp. 11 ◽  
Author(s):  
Pankaj Joshi ◽  
Oliver Willekens ◽  
Xiaobing Shang ◽  
Jelle De Smet ◽  
Dieter Cuypers ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Beam Steering ◽  
Polymer Dispersed ◽  
Phase Liquid ◽  
Blue Phase ◽  
Blue Phases ◽  
Polymer Stabilized ◽  
Polarization Independent

A polarization independent and fast electrically switchable beam steering device is presented, based on a surface relief grating combined with polymer stabilized blue phase liquid crystals. Switching on and off times are both less than 2 milliseconds. The prospects of further improvements are discussed. Full Text: PDF ReferencesD.C. Wright, et al., "Crystalline liquids: the blue phases", Rev. Mod. Phys. 61, 385 (1989). CrossRef H. Kikuchi, et al., "Polymer-stabilized liquid crystal blue phases", Nat. Mater. 1, 64 (2002). CrossRef Samsung, Korea, SID exhibition, (2008).J. Yan, et al., "Direct measurement of electric-field-induced birefringence in a polymer-stabilized blue-phase liquid crystal composite", Opt. Express 18, 11450 (2010). CrossRef L. Rao, et al., "A large Kerr constant polymer-stabilized blue phase liquid crystal", Appl. Phys. Lett. 98, 081109 (2011). CrossRef Y. Hisakado, et al., "Large Electro-optic Kerr Effect in Polymer-Stabilized Liquid-Crystalline Blue Phases", Adv. Mater. 17, 96 (2005). CrossRef K. M. et al., "Submillisecond Gray-Level Response Time of a Polymer-Stabilized Blue-Phase Liquid Crystal", J. Disp. Technol. 6, 49 (2010). CrossRef Y. Chen, et al., "Level set based topology optimization for optical cloaks", Appl. Phys. Lett. 102, 251106 (2013). CrossRef H. Choi, et al., "Fast electro-optic switching in liquid crystal blue phase II", Appl. Phys. Lett. 98, 131905 (2011). CrossRef Y.H. Chen, et al., "Polarization independent Fabry-Pérot filter based on polymer-stabilized blue phase liquid crystals with fast response time", Opt. Express 19, 25441 (2011). CrossRef Y. Li, et al., "Polarization independent adaptive microlens with a blue-phase liquid crystal", Opt. Express 19, 8045 (2011). CrossRef C.T. Lee, et al., "Design of polarization-insensitive multi-electrode GRIN lens with a blue-phase liquid crystal", Opt. Express 19, 17402 (2011). CrossRef Y.T. Lin, et al., "Mid-infrared absorptance of silicon hyperdoped with chalcogen via fs-laser irradiation", J. Appl. Phys. 113, (2013). CrossRef J.D. Lin, et al., "Spatially tunable photonic bandgap of wide spectral range and lasing emission based on a blue phase wedge cell", Optics Express 22, 29479 (2014). CrossRef W. Cao, et al., "Lasing in a three-dimensional photonic crystal of the liquid crystal blue phase II", Nat. Mat. 1, 111 (2002). CrossRef S.T. Hur, et al., "Liquid-Crystalline Blue Phase Laser with Widely Tunable Wavelength", Adv. Mater. 25, 3002 (2013). CrossRef A. Mazzulla, et al., "Thermal and electrical laser tuning in liquid crystal blue phase I", Soft. Mater. 8, 4882 (2012). CrossRef C.W. Chen, et al., "Random lasing in blue phase liquid crystals", Opt. Express 20, 23978 (2012). CrossRef O. Willekens, et al., "Ferroelectric thin films with liquid crystal for gradient index applications", Opt. Exp. 24, 8088 (2016). CrossRef O. Willekens, et al., "Reflective liquid crystal hybrid beam-steerer", Opt. Exp. 24, 1541 (2016). CrossRef M. Jazbinšek, et al., "Characterization of holographic polymer dispersed liquid crystal transmission gratings", J. Appl. Phys. 90, 3831 (2001). CrossRef C.C. Bowley, et al., "Variable-wavelength switchable Bragg gratings formed in polymer-dispersed liquid crystals", Appl. Phys. Lett. 79, 9 (2001). CrossRef Y.Q. Lu, et al., "Polarization switch using thick holographic polymer-dispersed liquid crystal grating", Appl. Phys. 95, 810 (2004). CrossRef J.J. Butler et al., "Diffraction properties of highly birefringent liquid-crystal composite gratings", Opt. Lett. 25, 420 (2000). CrossRef R.L. Sutherland et al., "Electrically switchable volume gratings in polymer-dispersed liquid crystals", Appl. Phys. Lett. 64, 1074 (1994). CrossRef X. Shang, et al., "Electrically Controllable Liquid Crystal Component for Efficient Light Steering", IEEE Photo. J. 7, 1 (2015). CrossRef J. Yan, et al., "Extended Kerr effect of polymer-stabilized blue-phase liquid crystals", Appl. Phys. Lett. 96, 071105 (2010). CrossRef H.S. Chen, et al., "Hysteresis-free polymer-stabilized blue phase liquid crystals using thermal recycles", Opt. Mat. Exp. 2, 1149 (2012). CrossRef J. Yan. et al., "Dual-period tunable phase grating using polymer stabilized blue phase liquid crystal", Opt. Lett. 40, 4520 (2015). CrossRef H.S. Chen, et al., "Hysteresis-free polymer-stabilized blue phase liquid crystals using thermal recycles", Opt. Mat. Exp. 2, 1149 (2012). CrossRef H.C. Cheng, et al., "Blue-Phase Liquid Crystal Displays With Vertical Field Switching", J. Disp. Technol. 8, 98 (2012). CrossRef

Wide-angle nonmechanical beam steering using thin liquid crystal polarization gratings

2008 ◽  
Author(s):  
Jihwan Kim ◽  
Chulwoo Oh ◽  
Michael J. Escuti ◽  
Lance Hosting ◽  
Steve Serati
Keyword(s):  
Liquid Crystal ◽  
Beam Steering ◽  
Wide Angle ◽  
Polarization Gratings

scholarly journals Observing and controlling a Tamm plasmon at the interface with a metasurface

Nanophotonics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 897-903 ◽  
Author(s):  
Oleksandr Buchnev ◽  
Alexandr Belosludtsev ◽  
Victor Reshetnyak ◽  
Dean R. Evans ◽  
Vassili A. Fedotov
Keyword(s):  
Liquid Crystal ◽  
Metal Film ◽  
Near Infrared ◽  
Thin Metal Film ◽  
Outer Side ◽  
Spectral Position ◽  
External Perturbations ◽  
Dielectric Mirror ◽  
Wavelength Scale ◽  
Sub Wavelength

AbstractWe demonstrate experimentally that Tamm plasmons in the near infrared can be supported by a dielectric mirror interfaced with a metasurface, a discontinuous thin metal film periodically patterned on the sub-wavelength scale. More crucially, not only do Tamm plasmons survive the nanopatterning of the metal film but they also become sensitive to external perturbations as a result. In particular, by depositing a nematic liquid crystal on the outer side of the metasurface, we were able to red shift the spectral position of Tamm plasmon by 35 nm, while electrical switching of the liquid crystal enabled us to tune the wavelength of this notoriously inert excitation within a 10-nm range.

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