We present polarization-independent optical shutters with a sub-millisecond switching time. The approach utilizes dual-frequency nematics doped with a dichroic dye. Two nematic cells with orthogonal alignment are driven simultaneously by a low-frequency or high-frequency electric field to switch the shutter either into a transparent or a light-absorbing state. The switching speed is accelerated via special short pulses of high amplitude voltage. The approach can be used in a variety of electro-optical devices.
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http://dx.doi.org/10.1364/OE.27.003861 | DOI Listing |
J Colloid Interface Sci
December 2024
School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an 710129, China. Electronic address:
Phys Chem Chem Phys
December 2024
Department of Physics, University of Colorado, Boulder, Colorado, 80309, USA.
We show that stable, freely suspended liquid crystal films can be made from the ferroelectric nematic (N) phase and from the recently discovered polar, lamellar SmZ and SmA phases. The N films display two-dimensional, smectic-like parabolic focal conic textures comprising director/polarization bend that are a manifestation of the electrostatic suppression of director splay in the film plane. In the SmZ and SmA phases, the smectic layers orient preferentially normal to the film surfaces, a condition never found in typical thermotropic or lyotropic lamellar LC phases, with the SmZ films exhibiting focal-conic fan textures mimicking the appearance of typical smectics in glass cells when the layers are oriented normal to the plates, and the SmA films showing a texture of plaquettes of uniform in-plane orientation where both bend and splay are suppressed, separated by grain boundaries.
View Article and Find Full Text PDFbioRxiv
November 2024
Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA.
Cell patterning is essential for organized tissue development, enabling precise geometric arrangement of cells, body axis establishment and developmental timing. Here we investigate the role of physical forces and mechanical cues in organizing and maintaining cell morphological patterns during hindbrain neuropore closure, a critical morphogenetic event in vertebrate development. Through live-imaging in mouse embryos and cell-based biophysical modeling, we demonstrate that active cell crawling and actomyosin purse-string contraction at the neuropore border are insufficient to account for the observed cellular arrangements in space and time.
View Article and Find Full Text PDFThe alignment control of liquid crystals (LCs) is critical for various practical applications. The pretilt angle modulation of LCs typically requires a mechanical rubbing on substrates to orient the LCs. This study presents a contact-free approach to achieve pretilt angle modulation of LCs.
View Article and Find Full Text PDFSoft Matter
November 2024
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
We deploy optical microscopy with and without an applied magnetic field to characterize the three-dimensional morphology and measure the line tension of twist disclinations in twisted nematic liquid crystal (LC) sample cells. Twist disclinations are generated by quenching the LC, 5CB (4-cyano-4'-pentylbiphenyl), into the nematic phase; 5CB is confined between substrates with in-plane anchoring directions perpendicular to one another. The disclinations form loops separating domains of opposite twist handedness.
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