Anatoliy Glushchenko

University of Colorado Colorado Springs, Colorado Springs, Colorado, United States

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Publications (9)17.18 Total impact

  • Yuriy Garbovskiy, Anatoliy Glushchenko
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    ABSTRACT: In this paper, we will explore how optical and ferroelectric properties of the stressed ferroelectric nanoparticles prepared through ball milling set a limit on the performance of optical and electro-optical devices based on such materials. It was found that suspensions of BaTiO<sub>3</sub> nanoparticles exhibit a blue shift in the optical band gap with a decrease in particle size. The optical band gap of PbTiO<sub>3</sub> nanoparticles is not affected by the milling time. Polarization switching is composed of slow and fast components. A slow component is threshold-less and is caused by the particle reorientation while a fast component has a threshold, and its rise time is inversely proportional to the electric field. The absorption edge of these suspensions accounts for the applications in the near UV range, while kinetics of the polarization switching governs the speed of electro-optical devices.
    Applied Optics 08/2013; 52(22):E34-9. · 1.69 Impact Factor
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    Yuriy Garbovskiy, Anatoliy Glushchenko
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we will explore how optical and ferroelectric properties of the stressed ferroelectric nanoparticles prepared through ball milling set a limit on the performance of optical and electro-optical devices based on such materials. It was found that suspensions of BaTiO3 nanoparticles exhibit a blue shift in the optical band gap with a decrease in particle size. The optical band gap of PbTiO3 nanoparticles is not affected by the milling time. Polarization switching is composed of slow and fast components. A slow component is threshold-less and is caused by the particle reorientation while a fast component has a threshold, and its rise time is inversely proportional to the electric field. The absorption edge of these suspensions accounts for the applications in the near UV range, while kinetics of the polarization switching governs the speed of electro-optical devices.
    Applied Optics 08/2013; 52(22). · 1.69 Impact Factor
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    ABSTRACT: There are two switching processes where observe in polymer-dispersed liquid crystals (PDLC) when pulse electric field applied: - Slow switching process with rise time hundreds microseconds; - Fast switching process with nanoseconds rise time. The result of research, design and testing ultra-fast PDLC optical gate is presented. The feasibility of 100 nsec rise time optical gate with 1 square inch crystal clear transmission (better than 1.54 dB) and attenuation in OFF state more than 26 dB (30.4 dB for two serial layers) for non-polarized light has been shown.
    Proc SPIE 03/2013;
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    ABSTRACT: Liquid crystal (LC)/magnetic nanorods colloids were fabricated and tested using a magneto-optical setup. These thermotropic ferronematics do not show any signs of macroscopic aggregation, exhibit enhanced magnetic sensitivity, and faster time response in the simultaneous presence of crossed electric and magnetic fields. Magnetic nanorods increase an effective magnetic anisotropy of the colloid and decrease magnetic Freedericksz threshold. Applying a magnetic field along the direction perpendicular to the applied electric field leads to a decrease of the time OFF by a factor of 6 for pure liquid crystals, and by a factor of 9—for ferronematics.
    Applied Physics Letters 11/2012; 101(18). · 3.79 Impact Factor
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    ABSTRACT: We demonstrate an on-wafer liquid crystal phase shifter which has a tunable 0–300°/cm phase shift at 110 GHz. The results show no dispersion over the entire frequency range indicating a tunable “true time delay” of up to 2.5 ps/cm at all frequencies. The inherent losses in the liquid crystal are small, less than 1 dB/cm over the range of 1–110 GHz. The full tunability is achieved using small voltages, close to 10 V. We anticipate that one could achieve a phase shift of 600°/cm at 220 GHz.
    Journal of Applied Physics 03/2012; 111(5). · 2.21 Impact Factor
  • Yuriy Garbovskiy, Olena Zribi, Anatoliy Glushchenko
    01/2012; , ISBN: ISBN: 978-953-51-0885-6
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    ABSTRACT: Nearly all liquid crystal devices use a rubbed organic layer as a method of orienting the liquid crystals. This letter studies the alignment of nematic liquid crystals by rubbed and nonrubbed metallic surfaces. For rubbed metallic films, a homogeneous planar alignment of liquid crystals is found. Nonrubbed metallic surfaces align liquid crystals nonuniformly and randomly. The alignment produced by a single rubbed metallic surface extends from 10 to 50 μ m and is stable in time. These results are important because they show that the organic layer may be eliminated for some applications, including tunable microwave and infrared signal processing elements.
    Applied Physics Letters 03/2011; · 3.79 Impact Factor
  • Yuriy Garbovskiy, Anatoliy Glushchenko
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    ABSTRACT: Nanoparticle/liquid crystal colloidal dispersions are a new, rapidly developing, and exciting frontier of soft matter science and technological progress. This is both because of the dramatic changes in liquid crystal characteristics caused by adding nanoparticles and because of the limited understanding of the structure and interactions of the components of such composite systems. In this review, we summarize the basic science and applications of various nanoparticles, 1–100 nm in diameter, dispersed in liquid crystals. The historical development of this area of science is divided into two main periods. The first period, from the early 1970s until the year 2000, covers the structural organization and the interaction of passive nanoparticles (mostly dielectric) dispersed in liquid crystals. This period initiated the development of novel electro-optic effects and devices based on the properties of such composites. The second period covers progress during the first decade of the millennium. It is a Renaissance era in the development of liquid crystalline nanocolloids when the power of nanoscale was demonstrated to the full extent. Active nanoparticles, mostly ferroelectric, ferromagnetic, and ferroic, added to liquid crystals, shared their intrinsic properties with the liquid crystal host, and allowed for the creation of unprecedented materials with astonishing applications. These active particles generate ultrahigh electric and/or magnetic fields within the liquid crystal host, which, combined with their small size, produces a uniquely exciting and largely unexplored system of composite materials which exhibit novel collective particle–host interactions and which promise a variety of exotic electro-magneto-optic and other applications. These internally generated fields, larger than any macroscopic field that can be applied, serve both to spatially organize the particles and to couple the particle system to the liquid crystal thus enabling the liquid crystal ordering to affect the collective particle order. Although we have made an effort to review liquid crystalline/nanocolloids research as broadly as possible, many great results are omitted from this chapter. We hope this review will be an invitation to further explore this unique and exiting collection of knowledge.
    Solid State Physics 01/2010; 62:1-74. · 4.00 Impact Factor
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    ABSTRACT: Liquid crystal alignment is a key process in the production of modern display devices and other liquid crystal based optical elements. The traditional alignment procedures, dealing with treatment of organic films (rubbing, photo-polymerization, ion beam treatment, etc), do not satisfy the increasing demands of modern technology. Because of the presence of a degradable polymer layer, none of these methods provides stability of the liquid crystal orientation for operation in high intensity visible, UV or infrared light. This problem can be solved using anisotropically treated inorganic thin films. The alignment is very sensitive; both polar and azimuthal anchoring energy parameters can be controlled by either conditions of the treatment process or the history of the inorganic film formation. The non-organic nature of the substrates provides non-degrading stability of the liquid crystals alignment while operating in high intensity visible, UV or infrared light. We demonstrate and discuss the use of this technology in many light modulating devices, including high intensity light phase retarders and displays operating at harsh ambient conditions.
    Proc SPIE 05/2009;