Browsing by Author "Zyryanov, Victor Ya"

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Electro-optical response of an ionic-surfactantdoped nematic cell with homeoplanar-twisted configuration transition
(2014-04-01)
Sutormin, Vitaly S.
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Krakhalev, Mikhail N.
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Prishchepa, Oxana O.
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Lee, Wei
;
Zyryanov, Victor Ya
This study is concerned with the optical response of an electro-optical material consisting of nematic liquid crystal as well as ionic surfactant as a dopant. The dopant is a key component to carry out the working of the resulting device through configuration switching. The operational principle is based on the surface anchoring transition induced by a steady electric field. The dynamic characteristics of the electro-optical cell can be considerably improved when the nematic layer is reoriented from the initially homeoplanar director configuration into the twisted state. Besides, a method to shorten the relaxation time is demonstrated by using a controlling pulse with a bipolar waveform. (C)2014 Optical Society of America
Enhanced light absorption with a cholesteric liquid crystal layer
(2013-04-01)
Timofeev, Ivan V.
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Arkhipkin, Vasily G.
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Vetrov, Stepan Ya
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Zyryanov, Victor Ya
;
Lee, Wei
We discuss the trapping features of cholesteric liquid crystal as a self-organized photonic crystal and suggest it for absorption improvement. The imperfection of the absorbing surface is manifested by the reflection originating from the indispensable impedance mismatch. The reflection can be suppressed by an additional surface coating to reflect the light back to the absorber once again. In the simple consideration this reflection loop is possible only twice. For a right-handed CLC coating, the boundary reflection switches the light polarization from left to right circular in the first loop and it switches in the second loop back to the left circular polarization before the emerging light finally escapes from the absorbing process. The enhancement of light absorption is possible in the frequency range as large as the photonic bang gap of the cholesteric layer, which can be adjusted as desired. (C) 2013 Optical Society of America
Hybrid anchoring for a color-reflective dual-frequency cholesteric liquid crystal device switched by low voltages
(2015-11-01)
Hsiao, Yu-Cheng
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Timofeev, Ivan V.
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Zyryanov, Victor Ya
;
Lee, Wei
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影像與生醫光電研究所
Cholesteric liquid crystal (CLC) materials used in electro-optical (EO) devices are characterized by high operating voltage and slow response speed, which hinders their further development in display applications. Dual-frequency CLCs (DFCLCs) can solve the problem of slow bistable transition, but the operating voltage is still high, especially in color-reflective DFCLC cells. Here we report a simple approach to lowering the switching voltage as well as to shortening the response time. This technique adopts hybrid surface treatment to modulate the structural arrangement of CLC molecules. Both planar-and vertical-alignment layers are employed and coated on one and the other substrates separately to improve the electro-optical properties of DFCLCs. We show that the threshold voltage for switching can be decreased to as low as 5 V and the shortest response time is measured to be 0.8 ms, which renders CLC EO devices including displays more practical for commercial purpose. (C) 2015 Optical Society of America