Deformed Helix Ferroelectric Research Articles

Broad temperature range ferrielectric liquid crystal: Temperature dependencies of dielectric and electro-optical properties

Broad temperature range ferrielectric liquid crystal mixture FerriLCM-1 was previously developed in 2022 (Pozhidaev et al. 2022). In that work dielectric and electro-optical properties of the mixture were studied at room temperature. Electrically induced birefringence index reached 0.01 at a wavelength of 532 nm with response times of 300 μs. In this paper we continue the FerriLCM-1 properties investigation in a wide temperature range from the room ones till the isotropic phase transition temperature. It is found that one of the critical electric fields is almost temperature independent, while the Kerr coefficient of quadratic electro-optical effect in deformed helix ferroelectric (DHF) mode grows with temperature increase. This leads to an increase in the depth of phase modulation. Another critical electric field decreases smoothly with temperature rising. At 47–50 °C two critical electric fields merge, while temperature dependencies of all other dielectric and electro-optical parameters of the mixture are continuous and smooth functions. At about 50 °C the maximum electrically induced birefringence in DHF-mode is ΔneffE=0.022 under the applied electric field E=0.4 V/μm and with 80 μs response time. FerriLCM-1 mixture operating in the DHF-mode exhibits a giant Kerr coefficient of 1700 nm/V2 (or even up to 2900 nm/V2 at λ=400nm) at the temperature of 85 °C combined with a 50 μs response time. This is the highest value of Kkerr coefficient among liquid crystals. All these properties make ferrielectric liquid crystal mixture FerriLCM-1 suitable for solving various problems of phase modulation of light and use in low-voltage devices.

Single ferroelectric liquid crystal compounds targeted for optical voltage sensing

Nine compounds containing fluorine or chlorine atoms in the lateral position in the rigid core with a chiral terminal octyloxy-chain were synthesized mainly using Suzuki-Miyaura coupling, Mitsunobu, hydrogenation, and esterification reactions. New compounds were investigated using polarized optical microscopy (POM), differential scanning calorimetry (DSC), spectrophotometry, and electro-optical methods. A computational analysis of the effect of lateral substitution by halogen atoms on the phenyl ring on the dipole moment of the compound was provided and discussed. The designed compounds exhibit a wide temperature range of the ferroelectric phase (>40.0 °C), a low melting point (in most cases below 50.0 °C), low melting enthalpy (around 10.0–20.0 kJ/mol), a short helical pitch (in most cases below 200 nm at room temperature) and high tilt angle that ensures a cone angle of up to 90°; all those properties make them of great potential for the deformed helix ferroelectric (DHF) mode. Revealed features allow synthesized compounds in fully integrated polarization-based photonic transducers to have excellent linearity and the highest sensitivity observed in ferroelectric liquid crystals for DHF mode. For the first time, the DHF effect was reached for the single molecule FLC material in a broad temperature range down to 38 °C. These findings pave the way for a new class of optical sensors for, among others, industrial monitoring networks and brain/machine interfaces with unprecedented performance.

Reconfigurable Geometrical Phase Spatial Light Modulator Using Short‐Pitch Ferroelectric Liquid Crystals

AbstractThis article presents an approach to achieve a fast and analog geometrical phase modulation based on the optical axis rotation of the defect‐free Deformed Helix Ferroelectric Liquid Crystal (DHFLC) with a short pitch. This study demonstrates a Spatial Light Modulator (SLM) prototype with a feature size of 3 µm without Fringe Field Effect (FFE), having a phase depth of 1.9π, fast switching time (<250 µs) at a low operating voltage (<7 V), and high diffraction efficiency (>77%). The high phase modulation depth is achieved by developing DHFLC with a cone angle of up to 85˚, which is inherently immune to FFE. The ellipticity is minimized by using a compensation film that can suppress the changes in birefringence under the applied electric field. The proposed SLM is promising in applications such as a real‐time hologram and dynamic beam steering in Light Ranging and Detector (LiDAR).

33.2: Invited Paper: New electrooptical modes in photoaligned ferroelectric liquid crystals: physics and applications

The development of novel photoaligned fast ferroelectric LCD based on Deformed Helix Ferroelectric (DHF) and Electrically Suppressed Helix (ESH) mode is discussed. A fast response time and a high contrast ratio in ESH mode was observed. These modes can be successfully used for new FLC applications

Electro-optic and dielectric properties of polymer networks stabilised short pitch chiral smectic C* liquid crystal

ABSTRACT We present the effect of polymer network on the ferroelectric phase for a polymer stabilised ferroelectric liquid crystal (PSFLC) system. The ferroelectric liquid crystal (FLC) exhibits a very short helical pitch, large tilt angle and relatively high spontaneous polarisation. Electro-optic and dielectric investigations are performed on films with various polymer concentrations. Measurements in the chiral smectic C* (SmC*) phase of the tilt angle and spontaneous polarisation as a function of electric field strength and polymer concentrations were performed. For low electric fields, a deformed helix ferroelectric (DHF) process was observed for pure FLC as well as for the PSFLC films, showing a linear response of the helical structure to electric field. The influence of the polymer network on the FLC properties is also investigated by linear dielectric measurements. Particularly the Goldstone relaxation mechanism. The results reveal a gradual decrease of the dielectric strength with an increase in the network density. However, the relaxation frequency of this mechanism seems to be insensitive to the polymer network density. These behaviours were interpreted by the increase of both the effective elasticity and the rotational viscosity of the SmC* when stabilised by the polymer network.

Ferroelectric Liquid Crystals: Physics and Applications

Electrooptic modes with fast response and high contrast ratio are highly desirable in modern photonics and displays. Ferroelectric liquid crystals (FLCs) are especially promising for fulfilling these demands by employing photoalignment technology in FLC cells. Three electrooptic modes including surface stabilized FLC (SSFLC), deformed helix ferroelectric (DHF) mode, and electrically suppressed helix (ESH) mode are reviewed with the corresponding electrooptic effects like bi- and multi-stable switching, continuous modulation of grayscale or phase, and high contrast switching. The general operation principles FLC electrooptic modes are described, and then the characteristics of each modes for potential applications are summarized. With the advantages of controllable anchoring energy, the photoalignment provides FLC samples with uniform alignment and high contrast ratio. The fast FLCs with a high resolution and high contrast can be used in the next generation display including field sequential color FLC microdisplays, as well as switchable 2D/3D televisions.

The quadratic electro-optical effect in ferroelectric liquid crystal helical nanostructures: role of the driving voltage shape

ABSTRACTRecently it was shown that in deformed helix ferroelectric (DHF) structure, the electrically controlled birefringence of chiral smectic C* phase with subwavelength helix pitch ( is known to be proportional to the square of the electric field E) depends on the cell thickness and on the frequency of applied voltage, given as a Step function of the time. The purpose of the present work is to investigate whether this quadratic effect depends also on the voltage function shape, comparing the electrically controlled birefringence and the Kerr constant in DHF cells with different thickness, driven by STAIR and Step voltage functions.

Ferroelectric liquid crystals: Excellent tool for modern displays and photonics

AbstractThe ferroelectric liquid crystals, because of their fast electro‐optical response, are one of the most important classes of liquid crystals. Here, in this review, we have summarized the different electro‐optical modes for ferroelectric liquid crystals. Clark–Lagerwall effect (surface stabilized ferroelectric liquid crystal), deformed helix ferroelectric (DHF) effect, electrically suppressed helix (ESH) mode, DHF orientational Kerr effect, and ESH diffraction modes have been discussed. All of the crucial features, that is, optics, electro‐optics, dynamics, and their dependence on material parameters, operational regime, and applications, have been reviewed.

Ferroelectric Liquid Crystal Cells for Advanced Applications in Displays and Photonics

Ferroelectric Liquid Crystals (FLC) are discussed for various applications in displays and photonics. We have considered new FLC electrooptic modes based on photoalignment technology: deformed helix ferroelectric (DHF) FLC, Electrically Suppressed Helix (ESH) and Voltage Controllable Diffraction (VCD) FLC Mode. New FLC display and photonics devises such as field sequential color (FSC) FLC displays, switches, grating, Fresnel lens, Circular Dammann (CD) grating are discussed. Certain comparison between ferroelectric and nematic LC devices is provided.

Reflective mode of deformed-helix ferroelectric liquid crystal cells for sensing applications

We present a detailed theoretical and experimental study of the reflectance response of a deformed-helix ferroelectric (DHF) liquid crystal (LC) cell to an applied voltage under cross-polarisers. Using a model based on the effective dielectric tensor approximation, we derive simple analytical formulas to design a LC cell with maximum modulation depth and optimal linearity of the electro-optical response intensity versus the electric field. Our experimental results show that the cell works at frequencies up to 10 kHz and exhibits excellent linearity, with a total harmonic distortion as low as −70 dB. These findings suggest that DHF-LCs can be exploited to develop simple and accurate optical sensors.

Voltage Sensor with wide Frequency Range using Deformed Helix Ferroelectric Liquid Crystal

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

Influence of Electric Field on the Orientation of Ferroelectric Liquid Crystals inside micro capillaries

In the paper we present recent results on investigation of ferroelectric liquid crystals molecules orientation inside photonic crystal fibers, which consist of a set of micro capillaries. We have infiltrated glass micro capillaries with different inner diameters with the experimental ferroelectric liquid crystal mixture W-206K. The orientation of the liquid crystal molecules was controlled by the external electric field applied to the sample. We have obtained promising results about the orientation of the ferroelectric liquid crystal molecules and their behavior under influence of applied external electric field. The presented results may lead to design a new class of fast-switching fiber optic sensors. Full Text: PDF References P. St.J. Russell, "Photonic-Crystal Fibers", J. Lightwave Technol. 24, 4729-4749 (2006). CrossRef T. Larsen, A. Bjarklev, D. Hermann, and J. Broeng, "Optical devices based on liquid crystal photonic bandgap fibres", Opt. Express 11, 2589-2596 (2003). CrossRef T. R. Wolinski, K. Szaniawska, K. Bondarczuk, P. Lesiak, A.W. Domanski, R. Dabrowski, E. Nowinowski-Kruszelnicki, J. Wojcik, "Propagation properties of photonic crystal fibers filled with nematic liquid crystals", Opto-Electronics Rev. 13(2), 177-182 (2005). DirectLink M.W. Haakestad, et al., "Electrically tunable photonic bandgap guidance in a liquid-crystal-filled photonic crystal fiber", IEEE Photon. Technol. Lett. 17, 819–821 (2005). CrossRef Matuszczyk M. "Structures and Properties of Ferroelectric Liquid Crystal Displays", Goteborg, Sweden, Chalmers Reproservice (1996). Q. Guo, E. P. Pozhidaev, A. K. Srivastava, Y. Ma, X. Wang, V. G. Chigrinov, H. S. Kwok, "Deformed Helix Ferroelectric Display with Low Driving Voltage and Fast Response Time", SID Symposium Digest of Technical Papers, Vol. 43 (1), 449-451, (2012). CrossRef E. P. Pozhidaev et al., "High Frequency Low Voltage Shock-Free Ferroelectric Liquid Crystal: A New Electro-Optical Mode with Electrically Suppressed Helix", Proc. of 31-th International Display Research Conference EuroDisplay 2011, Bordeaux-Arcachon, France, September 19-22 (2011). DirectLink Vladimir Chigrinov, Eugene Pozhidaev, Abhishek Srivastava, Guo Qi, Ma Ying, Hoi Sing Kwok, "Fast Ferroelectric Liquid Crystal Modes Based on Photoaligning Technology", SID 2013, Vancouver, Canada, May 2013 Clark, N. A. and S. T. Lagerwall, "Submicrosecond bistable electro-optic switching in liquid crystals", Appl. Phys. Lett. Vol. 36, 899-901(1980). CrossRef S. Mathews, Y. Semenova, G. Rajan, G. Farrell, "Tunable properties of Liquid Crystal filled Photonic Crystal Fibers", Proc. SPIE 7316, 73161E (2009). CrossRef D. Budaszewski, T.R. Woliński, M. A. Geday, J. M. Otón, "Photonic Crystal Fibers infiltrated with Ferroelectric Liquid Crystals", Phot. Lett. Poland 2(3) (2010). CrossRef

34.1: Deformed Helix Ferroelectric Display with Low Driving Voltage and Fast Response Time

AbstractIn this paper, the electrooptical behavior of deformed helix ferroelectric(DHF) liquid crystals is described. Fast response with low driving voltage is obtained. One of remarkable properties of DHF mode is frequency dependence of the electrooptical response time, which is really exists in our case. Experimental and simulation results are provided with good accordance. Variable anchoring energy is realized in experiment with photosensitive alignment material SD1. For the purpose of evaluate the influence of anchoring energy on alignment quality in DHF mode, the measurement of anchoring coefficient of alignment layer for short helix pitch FLC is proposed. The contrast ratio of 13000 with switching time of 113 μs is obtained at room temperature.

11.2: Fast Ferroelectric Liquid Crystal Modes for Field ‐Sequential‐ Color and 3D Displays

AbstractThe development of novel photoaligned fast ferroelectric LCD based on Deformed Helix Ferroelectric (DHF) and Electrically Suppressed Helix (ESH) mode is discussed. A high quality dark state of DHF FLCD has been obtained as well as V‐shape switching with a high frequency. A fast response time and a high contrast ratio in ESH mode was observed. The applications in Field Sequential Color (FSC) and 3D LCD are envisaged.

Spontaneous Polarization in Smectic A Phase of Carbon Nanotubes Doped Deformed Helix Ferroelectric Liquid Crystal

Observation of non-zero spontaneous polarization in paraelectric phase in multiwalled carbon nanotubes doped deformed helix ferroelectric LC is reported. Electro-optical response, spontaneous polarization, rotational viscosity, dielectric permittivity, dielectric loss factor, and electrical resistance of pure and multiwalled carbon nanotubes doped deformed helix ferroelectric LC have been measured. Non-zero spontaneous polarization in paraelectric phase has been attributed to the possible short range orientational order of deformed helix ferroelectric LC surrounding the multiwalled carbon nanotubes through surface anchoring and ionic impurities. The results presented will help to understand the basic mechanism of interaction of multiwalled carbon nanotubes with deformed helix ferroelectric LC.

Smectic nanostructures with typical size less than the visible light wavelength: physics and electro-optics

Very short helix pitch (p 0 ~150-200nm) ferroelectric liquid crystals (FLCs) have been developed. Electro-optical cells based on these mixtures are free from selective reflection and diffraction in the visible spectral range and therefore exhibit very perfect operation in deformed helix ferroelectric (DHF) mode. Two main electro-optical modes of DHF cells with sub-wavelength helix pitch are under consideration   Full text: PDF

High frequency and high voltage mode of deformed helix ferroelectric liquid crystals in a broad temperature range

A new electrooptical mode was discovered in Deformed Helix Ferroelectric (DHF) liquid crystal cells. This mode appears, if the driving voltage frequency and amplitude are rather high. The electrooptical response time τ0, 1-0, 9 is practically independent on temperature in a very broad range but it strongly depends on the driving voltage frequency.

Application of FLC/AFLC materials to active-matrix devices

The market of TFT-LCDs has been enlarged during the last 10 years. Notebook computers have been the main application. For this application, twisted nematic mode has been used and demands for other modes has been limited. However, larger size of LCDs for monitors or TV are expected to be the next most promising market. Drawbacks of the twisted nematic (TN) mode for this market were narrow viewing angle and slow switching speed. The viewing angle dependence was overcome by using compensation film or by using new LCD modes, for example in-plane switching mode. The slow response is the last drawback to be overcome to realize excellent moving pictures which will be seriously requested in the near future. Several methods have been proposed for fast response of LCDs. However, the applications of ferroelectric liquid crystalline or antiferroelectric liquid crystalline (AFLC) (FLC) materials to TFT-LCDs should be the most promising one. In this article, the authors will review the application of FLC/AFLC materials to TFT-LCDs, such as deformed helix ferroelectric (DHF) mode, twisted FLC mode, monostable FLC mode, APD mode and the application of frustrated phase. Next, the problems to be solved for the application of these materials to TFT devices will be discussed. Finally, the authors will demonstrate the 15″ XGA TFT-LCD using liquid crystalline material showing frustoelectric LC state, which is driven by newly developed driving technologies. Copyright © 2000 John Wiley & Sons, Ltd.

Electrically controlled birefringence of deformed helix ferroelectric liquid crystals

Dependencies of the effective birefringence Δneff:(λ, V) of deformed helix ferroelectric (DHF) liquid crystals on the light wavelength λ and supplied voltage V are investigated.

New ferroelectric displays and operation modes

We first review ferroelectric displays and novel operating modes recently developed in our laboratories and elsewhere. The displays include deformed helix ferroelectric (DHF)-LCDs in large-cell-gap configurations as well as double-layer LCDs in transmission and reflection combined with fixed or switched optical compensators. These configurations are applicable to all electro-optic effects which are based on the rotation of the optical axis in the plane of the device, e.g. surface stabilized, electroclinic, flexoelectro-optic or DHF-LCDs. Moreover, a new ferroelectric display is presented which we denominate Alternating Polarization Domain (APD)-display. The new display is based on a low-Ps ferroelectric liquid crystal configuration which spontaneously aligns such that very narrow parallel stripes with opposite direction of spontaneous polarization are generated in the plane of the display. The alignment does not require field-induced texture formation. APD-LCDs are shown to exhibit low driving voltages (2 volts), gray scale and short response times (300 μs). In combination with optical compensators active-matrix driven reflective APD_LCD-projectors with driving voltages of 5V are possible.