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Polarization Conversion With Elliptical Patch Nanoantennas, Feng Wang, Ayan Chakrabarty, Fred Minkowski, Kai Sun, Qi-Huo Wei Jul 2012

Polarization Conversion With Elliptical Patch Nanoantennas, Feng Wang, Ayan Chakrabarty, Fred Minkowski, Kai Sun, Qi-Huo Wei

Chemical Physics Publications

In this paper, we demonstrate arrays of optical patch nanoantennas can convert light polarization through reflection. By breaking the azimuthal symmetry, elliptical plasmonic patch nanoantennas exhibit both even and odd cavity modes, which can be expressed by Mathieu functions. It is shown that by properly orienting the incident polarization, a linearly polarized light in resonance with one cavity mode can be converted into an elliptical or circular polarization after reflection. Since the major cavity modes can be excited at all incident angles, the polarization conversion by these elliptical patch nanoantennas can be realized with wide range of incident angles.


Effect Of Trans-Cis Photoisomerization On Phase Equilibria And Phase Transition Of Liquid-Crystalline Azobenzene Chromophore And Its Blends With Reactive Mesogenic Diacrylate, Namil Kim, Quan Li, Thein Kyu Mar 2011

Effect Of Trans-Cis Photoisomerization On Phase Equilibria And Phase Transition Of Liquid-Crystalline Azobenzene Chromophore And Its Blends With Reactive Mesogenic Diacrylate, Namil Kim, Quan Li, Thein Kyu

Chemical Physics Publications

Photoisomerization-induced phase transition of neat liquid-crystalline azobenzene chromophore (LCAC) and its effect on phase diagrams of its mixtures with reactive mesogenic diacrylate monomer (RM257) have been investigated experimentally and theoretically. Upon irradiation with ultraviolet light, the nematic phase of LCAC transformed to isotropic, while the crystal phase showed corrugated textures on the surface (i.e., ripples). The phase-transition temperatures and corresponding morphologies of the blends have been investigated by means of differential scanning calorimetry and optical microscopy. A theoretical phase diagram of a binary nematic and crystalline system was constructed by self-consistently solving the combined free energies of Flory-Huggins, Maier-Saupe ...


Three-Dimensional Orientational Order In The Bulk And On The Surface Of Polymer Films And Its Effect On Liquid-Crystal Alignment, O. V. Yaroshchuk, Yu. Zakrevskyy, Satyendra Kumar, J. Kelly, Liang-Chy Chien, J. Lindau Jan 2004

Three-Dimensional Orientational Order In The Bulk And On The Surface Of Polymer Films And Its Effect On Liquid-Crystal Alignment, O. V. Yaroshchuk, Yu. Zakrevskyy, Satyendra Kumar, J. Kelly, Liang-Chy Chien, J. Lindau

Chemical Physics Publications

The correlation between orientation ordering of polymer chains in the bulk of polymer film and at the polymer-liquid-crystal (LC) interface has been studied to determine it's role in LC alignment. The bulk and surface ordering of polymer were investigated by null ellipsometry and x-ray reflectivity, respectively. Two kinds of liquid-crystalline polymers were used; side-chain azopolymers with azochromophores containing hydrophobic OC(4)H(9) alkyl chain (P1) and strongly polar NO(2) group (P2) as the end substituents. The uniaxial tilt orientation of azochromophores in the films of both polymers was induced by the oblique irradiation with unpolarized UV light ...


Deuteron Nmr Investigation Of A Photomechanical Effect In A Smectic-A Liquid Crystal, Boštjan Zalar, Oleg Lavrentovich, Huairen Zeng, Daniele Finotello Aug 2000

Deuteron Nmr Investigation Of A Photomechanical Effect In A Smectic-A Liquid Crystal, Boštjan Zalar, Oleg Lavrentovich, Huairen Zeng, Daniele Finotello

Chemical Physics Publications

Deuteron quadrupole-perturbed NMR is used to study the perturbation of orientational order in a smectic-A liquid crystal (octylcyanobiphenyl or 8CB) caused by photoinduced trans-to-cis isomerization of a photosensitive dopant (diheptylazobenzene or 7AB). The time and temperature dependences of the orientational order were independently studied for 8CB, 7AB, and their mixtures. Upon UV irradiation that causes trans-to-cis isomerization of 7AB, the orientational order parameter of the smectic-A phase is reduced. Relaxation in the dark exponentially restores the equilibrium value of the order parameter. The characteristic time for this process closely matches the lifetimes of the 7AB excited state. While ...


Tilted Photoalignment Of A Nematic Liquid Crystal Induced By A Magnetic Field, Denis Andrienko, Yuri Kurioz, Yuri Reznikov, Charles Rosenblatt, Rolfe Petschek, Oleg Lavrentovich, Darius Subacius Jan 1998

Tilted Photoalignment Of A Nematic Liquid Crystal Induced By A Magnetic Field, Denis Andrienko, Yuri Kurioz, Yuri Reznikov, Charles Rosenblatt, Rolfe Petschek, Oleg Lavrentovich, Darius Subacius

Chemical Physics Publications

Nematic liquid crystal cells with polyvinyl cinnamate coated substrates were subjected to ultraviolet light. When this was done in the presence of an oblique magnetic field the photoalignment was found to be temporally and thermally robust, with a large pretilt angle and weak polar anchoring. Moreover, two easy axes with equal and opposite pretilt angle were obtained, such that a magnetic field could switch the director from one easy axis to the other. (C) 1998 American Institute of Physics.