The terahertz time domain spectroscopy (THz-TDS) system is used to determine the effects of an AC bias voltage on tunable response a metamaterial transducer. tunability structure, which based rod-split-square resonator, demonstrated at frequencies through electrical control nematic liquid crystal orientation. Experimental results show that device can be tuned effectively (with transmittance change up 19%) by changing magnitude from 0 300 V. This type could find application in development...

A tunable graphene-based hyperbolic metamaterial is designed and numerically investigated in the mid-infrared frequencies. Theoretical analysis proves that by adjusting chemical potential of graphene from 0.2 eV to 0.8 eV, reflectance can be blue-shifted up 2.3 µm. Furthermore, modifying number monolayers stack, we are able shift plasmonic resonance 3.6 Elliptic type II dispersions shown for three considered structures. Importantly, a blue/red-shift switching reported at different incident...

Abstract Graphene-based hyperbolic metamaterials provide a unique scaffold for designing nanophotonic devices with active functionalities. In this work, we have theoretically demonstrated that the characteristics of polarization-dependent tunable microcavity in mid-infrared frequencies could be realized by modulating thickness dielectric layers, and thus breaking periodicity graphene-based metamaterial stack. Transmission shows Fabry–Perot resonant mode Q-factor > 20, sixfold local...

We present an electrically tunable metamaterial device consisting of a periodic array crossed elements embedded in nematic liquid crystal. Our experimental results show that the transmittance and absorption coefficient can be substantially tuned (with change up to 22% for 0.82 THz) by switching crystal alignment, induced applying external voltages applied wire electrodes. Structured devices may find applications modulation operating visible–infrared–terahertz microwave regimes.

In this Letter, we report on measurements of the complex permittivity highly anisotropic nematic liquid crystals at microwave frequencies as a function AC bias voltage. Permittivity have been performed by split post dielectric resonator technique. The experiments shown that when voltage increases from 0 to 8 V, real part these changes up 28%. tunability and relatively low losses observed in crystal mixtures mean they are ideal materials for design tunable components.

Surface-mediated director reorientation in a pure nematic liquid crystal (LC) cell the presence of both dc and low-power optical field has been observed. A surface-dependent lowering Friedericksz transition voltage planar upon light irradiation was found. It is believed that this effect due to light-induced change near-surface ion concentration photosensitive surface. Enrichment near surface causes redistribution electric its localization As consequence, energy interaction between LC...

The search for new low loss nematic liquid crystal mixtures with enhanced birefringence and temperature of nematic-to-isotropic phase transition plays a pivotal role in development applications the emerging field thermally tunable metamaterials. Here we maximize induced tunability terahertz metamaterial by using specially designed mixture. It is shown that resonant response device can be effectively tuned both terms its magnitude wavelength spectral approaching theoretical limit 8 GHz....

We show that a hybrid LC-ferroelectric nanoparticle suspension of liquid crystal E7 doped with BaTiO3 nanoparticles leads to 10% increase in birefringence the THz region spectrum as compared pure E7. Doped crystals can be used performance modulators and waveplates. mixture were synthesised sol gel technique, their refractive index has been measured powder form solution.

In this paper we report how dielectric spectroscopy can help in creating of dual-frequency nematic liquid crystals.Dual-frequency crystals is new class crystal materials.Such mixture usually formed by a combination many components (even more than 10), which be split into two groups: molecules having large transverse dipole moment and with longitudinal moment.The behavior base (parent) mixture, functional admixtures nal investigated wide frequency (100 Hz10 MHz) temperature ranges.This allows...

A split post dielectric resonator is used to determine the effect of AC bias voltage on microwave complex permittivity nematic liquid crystals. High resistivity silicon transducers separated by 100 μm are bridged crystals and their properties determined. The in-plane can be effectively tuned (change effective up 8%) increasing from 0 6 V. Using high allowed us obtain tunable stacks with relatively small losses at frequencies.

Abstract Epsilon‐near‐zero (ENZ) metamaterials represent a powerful toolkit for selectively transmitting and localizing light through cavity resonances, enabling the study of mesoscopic phenomena facilitating design photonic devices. In this experimental study, it demonstrates feasibility engineering actively controlling modes, as well tuning their mutual coupling, in an ENZ multilayer structure. Specifically, by employing high‐birefringence liquid crystal film tunable nanocavity,...

W1832A, a dual-frequency, multi-component nematic mixture prepared at the Military University of Technology, was investigated by means dielectric spectroscopy over wide frequency range (100 Hz–10 MHz) and temperature (−60°C–100°C). At −60°C it is still nematic. The changes sign anisotropy domains. High-precision studies molecular motions (around short (S) long (L) axes) were performed using cells 5 μm thickness. Gold electrodes in measuring spin-coated with agents for homogenous homeotropic...

In this article, optical properties of four fluoro-substituted 4-propyl-4′-[(4-ethylphenyl)ethynyl] biphenyls and liquid crystal mixture A are presented in the terahertz (THz) range. Birefringence, refractive indices absorption coefficients for ordinary extraordinary ray crystals described range 0.3 to 3.0 THz. It shows that measured parameters dependent on number placement fluorine atoms molecules. Measurements have been performed using time-pulsed spectroscopy.

We analysed the response of a tunable liquid crystal metamaterial transducer in terahertz frequency range. Tunability scattering parameters is achieving by an in-plane switching (IPS) effect. The structure based on Ω-shape resonators. A full-wave analysis technique finite-difference time-domain (FDTD) method was performed using QuickWave 3D electromagnetic solver. Terahertz transmission properties can be controlled director layer. effective refractive index for operation varies from negative...

In this article electromagnetic simulations of tunable terahertz metamaterial infiltrated with nematic liquid crystal are described. A full-wave analysis technique based on the finite-difference time-domain (FDTD) method was done by employing QuickWave 3D solver. Scattering parameter shows a resonant frequency shift 0.8 THz obtained reorienting layered highly birefringent crystal. Effective refractive index for operation varies from negative to positive values.

Dielectric singularities (DSs) constitute one of the most exotic features occurring in effective permittivity artificial multilayers called hyperbolic metamaterials (HMMs). Associated to DSs, a rich phenomenology arises that justifies ever-increasing interest profuse by photonic community achieving an active control their properties. As example, possibility "canalize" light down nanoscale as well capability HMMs interact with quantum emitters, placed proximity, enhancing emission rate...

Abstract Mesomorphic and dielectric properties of three homologous series two ring fluorosubstituted esters are described. They 4-cyano-3-fluorophenyl 4-alkyloxy-2-fluorobenzoates, 4-(4-alkylbenzoyloxy)-2-fluorobenzoates 3-fluoro-4-cyanophenyl, or 3-fluoro-4-isothiocyanatophenyl 3,4-difluorophenyl 4′-alkyl-2,3-difluoro-biphenyl-4-carboxylates. The compounds exhibit the nematic mesophase accompanied by smectic A C in some cases. Most them show strong dependence anisotropy Δε upon frequency,...

We analysed the response of a tunable liquid crystal metamaterial (MTM) transducer in terahertz frequency range. The MTM structure is based on rod double-split square resonators (SSR) with back-to-back orientation. A full-wave analysis technique finite-difference time-domain method (FDTD) was performed using QuickWave 3D electromagnetic solver. Terahertz transmission properties can be controlled by director layer. main aim this work to determine impact size SSR scattering parameters at...

Visualization of phase objects introducing small distortions to a plane wave front (such as turbulence air) can be realized with the well-known Zernike filtering. In this work we discuss and present use an optically addressed liquid crystal spatial light modulator (OA LC SLM) performing self-induced nonlinear Zernike-type The OA SLM is made planar nematic layer sandwiched between photoconductor (PVK:TNF 100-nm-thick polymer) polyimide orienting layer. advantage such filter over conventional...

Abstract Liquid crystals (LCs) with high optical anisotropy are very desirable for different applications in devices, such as filters, phase shifters, or gratings [T. Göbel, P. Meissner, A. Gaebler, M. Koeberle, S. Mueller, and R. Jakoby, Dual-Frequency Switching Crystal Based Tunable THz Filter, CLEO, Baltimore, MD, 2009; C.-Y. Chen, T.-R. Tsai, C.-L. Pan, R.-P. Room temperature terahertz shifter based on magnetically controlled birefringence liquid crystals, Appl. Phys. Lett. 83 (2003),...

Due to their unique electromagnetic properties, left-handed metamaterials (LHMs) have interesting potential application values at microwave frequencies. A tunable LHM employing nematic liquid crystal BL006 frequencies was analysed. full-wave analysis technique based on the finite-difference time-domain method (FDTD) performed using QuickWave software for a design program. Parameters of structure metamaterial such as transmission and effective refractive index show good agreement in relation...