Surface Stabilized Topological Solitons in Nematic Liquid Crystals

The present research explores nematicons in liquid crystals (LCs) with quadruple power law nonlinearity utilizing the modified extended Fan sub-equation technique as an analytical tool to investigate the optical spatial soliton solutions. For the inaugural time, a novel version of nonlinearity is investigated in relation to LCs. There are distinct applications for the several wave solutions that have been created in optical handling data. The aforementioned modified extended Fan subequation approach offers novel, comprehensive solutions that are relatively easy to deploy in comparison to earlier, regular methodologies. This approach translates a coupled non-linear partial differential equation into a coupled ordinary differential equation through implementing a traveling wave conversion. This approach indicates that a large variety of traveling and solitary solutions that rely upon five parameters can be incorporated by the nematicons in LCs. In addition, the investigation yields solutions of the single and mixed non-degenerate Jacobi elliptic function form. Novel solutions, such as the periodic pattern, kink and anti-kink patterns, N-pattern, W-pattern, anti-Z-pattern, M-pattern, V-pattern, complexion pattern and anti-bell pattern, or dark soliton solutions of nematic LCs, have been constructed by means of modified extended Fan subequation technique through granting suitable values for the parameters. The computer software Mathematica 14 is used to illustrate several modulus, real and imaginary solutions visually in the form of contour, 2D, and 3D visualizations that help understand the concrete importance of the nematicons in LCs. This research additionally offers a physical comprehension of the obtained solutions and applications of model. The imposed approach is ultimately thought to be more potent and effective than alternative approaches, and the solutions found in this work could be beneficial in our understanding of soliton structures in LCs.

Disclinations are among the most common topological defects in nematic liquid crystals. Their controlled generation is essential for both fundamental studies of defect physics and the development of functional soft-matter systems. However, achieving such control remains challenging. Here, we use laser thermal tweezers in a nematic liquid crystal cell with a free surface to generate a hybrid planar soliton, a structure topologically equivalent to a disclination, as both belong to the same homotopy group, π 1 ( R P 2 ). This soliton acts as a template for guiding the formation of disclinations with prescribed geometries and positions. To the best of our knowledge, this represents the first practical implementation of soliton–disclination conversion for direct and predictable defect control. These results elucidate the topological connection between planar solitons and disclinations and provide a foundation for precise topological patterning in liquid crystal systems.

We investigate interactions between spatial nonlocal bright solitons in nematic liquid crystals using an analytical ("effective particle") approach as well as direct numerical simulations. The model predicts attraction of out-of-phase solitons and the existence of their stable bound state. This nontrivial property is solely due to the nonlocal nature of the nonlinear response of the liquid crystals. We further predict and verify numerically the critical outwards angle and degree of nonlocality which determine the transition between attraction and repulsion of out-of-phase solitons.

In this work, a study is carried out to analyze nematicons in liquid crystals in the presence of Kerr and parabolic law nonlinearity. Exp(− $$\phi ({\xi })$$ )-Expansion method is incorporated in this regard. Solutions obtained include hyperbolic, periodic and rational solutions along with their combo type solutions in both cases of nonlinearity and their existence is guaranteed by the constraints retrieved during the process.

LIQUID CRYSTALS SPATIAL LIGHT MODULATORS FOR PRECISION OPTICSAPPLICATIONSTom BaurMeadowlark Optics, Inc.7460 Weld County Road 1Longmont, CO 80504-9470(303)776-4068, (303)776-5856 (FAX)Meadowlark Optics has developed a variety of spatial light modulators (SLMs) fornondisplay applications. They operate by electrical control of the birefringence of nematicliquid crystals to achieve spatial and temporal modulation of phase and amplitude of light.They modulate phase by electrically varying the effective extraordinary index, n, of auniaxial layer of nematic liquid crystal. This varies the optical thickness of the layer for lightthat is linearly polarized parallel to the optic axis of the layer. The SLM's can modulateamplitude for light that is linearly polarized at 45° to this direction if they are followed by anorthogonal or parallel linear polarizer.The electrical control of the effective n and thus the control of birefringence meansthat each means spatial element or pixel of the SLM functions as a variable retarder. Thefigure below shows the relationship between applied voltage and retardance of a typical liquidcrystal variable retarder. Notice that the relationship is nonlinear and that a fixed subtractiveretarder must be added to reach zero retardance. The maximum retardance depends on thethickness of the liquid crystal layer. Typical thicknesses range from 1 .5 microns to 30microns. Most nematic liquid crystals have a birefringence (n-n0) in therange of 0.05 to0.25. Therefore, the available range of electrical control of retardance and of opticalthickness can be from as little as 75 nm for a thin layer of low birefringence liquid crystal toas much as 7.5 microns for a thick layer of high birefringence liquid crystal.E=

We study a 2D system that couples a Schrödinger evolution equation to a nonlinear elliptic equation and models the propagation of a laser beam in a nematic liquid crystal. The nonlinear elliptic equation describes the response of the director angle to the laser beam electric field. We obtain results on well-posedness and solitary wave solutions of this system, generalizing results for a well-studied simpler system with a linear elliptic equation for the director field. The analysis of the nonlinear elliptic problem shows the existence of an isolated global branch of solutions with director angles that remain bounded for arbitrary electric field. The results on the director equation are also used to show local and global existence, as well as decay for initial conditions with sufficiently small L2−norm. For sufficiently large L2−norm we show the existence of energy minimizing optical solitons with radial, positive and monotone profiles.

Enhanced electrochemical and electro-optical properties of nematic liquid crystal doped with Ni:ZnCdS/ZnS core/shell quantum dots

Liquid crystal (LC) based spatial light modulators (SLM) offer a low cost alternative to the expensive deformable mirrors used in most adaptive optics systems. Real time correction of simulated atmospheric turbulence is demonstrated. The corrective element is a 10 by 10 pixel ferroelectric liquid crystal (FLC) SLM. An improvement in the Strehl ratio from 23% to 33% with a frame rate of 6Hz was demonstrated. A nematic liquid crystal (NLC) SLM was used to generate realistic atmospheric turbulence.

Short-focus nematic liquid crystal microlens array with a dielectric layer

Two designs of flexible triboelectric nanogenerators (TENGs) were successfully fabricated in three different configurations. Typically, TENG consists of anode layer, cathode layer, and electrodes. In design D1, configuration C1, the TENG was fabricated by assembling a flexible polyimide as an anode layer (bottom substrate), a flexible polyethylene terephthalate (PET) as a cathode layer (top substrate), copper (Cu) tapes as electrodes and glass as supporting layers for the top and bottom substrates. TENGs with configurations C2 and C3 were assembled by replacing cathode layer, PET, with a flexible thermoplastic polyurethane (TPU) and a flexible fabric, respectively. In design D2, configurations C1, C2 and C3 were assembled using same materials as in design D1, except anode layer, Kapton, was replaced with the polydimethylsiloxane (PDMS) sheet as bottom substrate. Multiple configurations were considered in order to determine the best material combination that would provide better TENG performance. The capability of the TENG in terms of open circuit voltage (V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</inf> ) and short circuit current (I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sc</inf> ) was demonstrated by subjecting it to ~ 5-6 Nm force at 10 Hz operating frequency. A maximum V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</inf> of 22.95 V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p-p</inf> , 30.44 V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p-p</inf> , power density of 0.31 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 0.46 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> were measured for the first and second designs, respectively. The TENG fabricated using PDMS and fabric exhibited a higher open circuit output.

In this paper we propose a new approach to fiber optic voltage sensors via voltage-controlled Liquid Crystals (LC), which would allow direct measurement of up to 400 kV/m electric fields at multiple points. In addition, the electro-optical behavior of deformed helix ferroelectric (DHF) liquid crystal in reflective mode is described and tested. The electrically controlled reflectance has been measured at sub-kilohertz driving voltage frequency for different polarizations of the incident light. Full Text: PDF References Y.V. Izdebskaya, V.G. Shvedov, A.S. Desyatnikov, W. Krolikowski and Y.S. Kivshar, "Soliton bending and routing induced by interaction with curved surfaces in nematic liquid crystals", Opt. Lett. 35, 1692-1694 (2010). CrossRef Z. Ge, S. Gauza, M. Jiao, H. Xianyu and S.T. Wu, "Electro-optics of polymer-stabilized blue phase liquid crystal displays", Appl. Phys. Lett. 94, 101104 (2009). CrossRef Z. Brodzeli, F. Ladouceur, L. Silvestri, A. Michie, V. Chigrinov, G. Q. Guo, E. P. Pozhidaev and A. D. Kiselev, "Liquid crystal-based hydrophone arrays", APOS (2012). CrossRef T. Tanigawa, Y. Sakakibara, S. Fang, T. Sekikawa and M. Yamashita, "Spatial light modulator of 648 pixels with liquid crystal transparent from ultraviolet to near-infrared and its chirp compensation application", Opt. Lett. 34, 1696-1698 (2009). CrossRef K. H. Yang and T. C. Chieu, "Transport Properties of Ions in Ferroelectric Liquid Crystal Cells", Jpn. J. Appl. Phys. 28, 2240-2246 (1989) CrossRef I.C. Khoo and S.T. Wu, "Optics and Nonlinear Optics of Liquid Crystals", World Scientific, Singapore (1993). V.G. Chigrinov, "Liquid Crystal Devices: Physics and Applications", Artech House, Boston: London, (1999). A.D. Kiselev, E.P. Pozhidaev, V.G. Chigrinov and H.S. Kwok, "Polarization-gratings approach to deformed-helix ferroelectric liquid crystals with subwavelength pitch", Phys. Rev. E 83, 31703 (2011). CrossRef N. A. Clark and S. T. Lagerwall, "Submicrosecond bistable electro-optic switching in liquid crystals", Appl. Phys. Lett. 36, 899-901 (1980). CrossRef L.A. Beresnev, V.G. Chigrinov, D.I. Dergachev, E.P. Pozhidaev, J. Funfshilling and M. Schadt, "Deformed helix ferroelectric liquid crystal display: A new electrooptic mode in ferroelectric chiral smectic C liquid crystals", Liq. Cryst. 5, 1171-1177 (1989). CrossRef Z. Brodzeli, H.K. Bal, V.G. Chigrinov, A. Murauski, and F. Ladouceur, "Electrical energy harvesting device for current/voltage fibre-based sensors", Optical Fibre Technology (ACOFT), 2010 35th Australian Conference on Fibre Technology, 1-2, (2010). DirectLink X. Zhao, F. Boussaid, A. Bermak and V.G. Chigrinov, "High-resolution thin ?guest-host? micropolarizer arrays for visible imaging polarimetry", Opt. Exp. 19, 5565-5573 (2011). CrossRef X.H. Li, A. Murauski, A. Muravsky, P.Z. Xu, H.L. Cheung, and V. Chigrinov, "Grayscale Generation and Stabilization in Ferroelectric Liquid Crystal Display," J. Display Technol. 3, 273-279 (2007). CrossRef E.P. Pozhidaev, S. Torgova, M. Minchenko, C. Yednak, A. Strigazzi and E. Miraldi, "Phase modulation and ellipticity of the light transmitted through a smectic C* layer with short helix pitch", Liq. Cryst. 37, 1067-1081, (2010). CrossRef E.P. Pozhidaev and V.G. Chigrinov, "Bistable and multistable states in ferroelectric liquid crystals", Crystallography Reports. 51, 1030-1040 (2006). CrossRef Q. Guo, F. Fan, T. Du, and V.G. Chigrinov, "Electrooptic Response of FLC: Effect of Alignment Materials", SID'11 Conference, P-144, Los Angeles, USA, May, (2011). CrossRef G. Hegde, P. Xu, E.P. Pozhidaev, V.G. Chigrinov, and H.S. Kwok, "Electrically controlled birefringence colours in deformed helix ferroelectric liquid crystals", Liq. Cryst. 35, 1137-1144 (2008). CrossRef

In a numerical study we investigate the influence of noise on the shape-invariant solitons in nematic liquid crystals. We use the modified Petviashvili’s method for finding eigenvalues and eigenfunctions of the evolution partial differential equations, to determine the shape-invariant solitons in a realistic scalar three-dimensional model that includes the highly nonlocal nature of uniaxial nematic liquid crystals. We check the stability of such solutions by propagating them for long distances, without or within the presence of white noise. Without noise, we find them stable. In the presence of noise (added to the medium), we find them breathing, which renders shape-invariant solitons difficult to observe. After prolonged propagation, the noise leads to the dissipation of solitons.KeywordsNematic Liquid CrystalOptical FieldLiquid Crystal CellSpatial SolitonMolecular ReorientationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Existence and stability of vector vortex solitons in nematic liquid crystals

Using He-Ne laser, semiconductor laser，and Ar+ laser as the light sources, we observed the self-focusing phenomena of light wave at low power and the forming of spatial solitons in nematic liquid crystal. The spatial solitons with a length over five millimeters and multiple-mode spatial optical solitons were viewed. Furthermore, the forming conditions and characteristics of these solitons were also discussed.

A great deal of interest over the years has been directed to the optical space solitons for the possibility of realizing 3D waveguides with very low propagation losses. A great limitation in their use for writing complex circuits is represented by the impossibility of making curved structures. In the past, solitons in nematic liquid crystals, called nematicons, were reflected on electrical interfaces, and more recently photorefractive spatial solitons have been, as well. In the present work, we investigate refraction and total reflection of spatial solitons with saturable electro-optic nonlinearity, such as the photorefractive ones, on an electric wall acting as a reflector. Using a custom FDTD code, the propagation of a self-confined beam was analyzed as a function of the applied electric bias. The electrical reflector was simulated by applying different biases in two adjacent volumes. We observed both smaller and larger angles of refraction, up to the critical π/2-refraction condition, and then the total reflection. The radii of curvature of the associated guides can be varied from centimeters down to hundreds of microns. The straight guides showed losses as low as 0.07 dB/cm as previously observed, while the losses associated with single curves were estimated to be as low as 0.2 dB.