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Achromatic Liquid Crystal Electro-Optical Devices Based On a Twisted Vertical Alignment Configuration

Chang, Kai-Han
http://orcid.org/0000-0002-7376-3397
http://rave.ohiolink.edu/etdc/view?acc_num=kent1523807996464507

Abstract Details

2018, PHD, Kent State University, College of Arts and Sciences / Chemical Physics.
Liquid crystal (LC) possesses the unique combination of optical and dielectric anisotropy, which makes it the choice of material for electro-optical (EO) device development. With different orientations defined by surface treatment and/or dopant in bulk, the resulting EO response provides abundant opportunities for innovative device development. In general, EO responses of liquid crystals are wavelength-dependent, making them challenging for displaying vivid color images without additional electronic or physical enhancement. In this dissertation, to mitigate the issue of wavelength-dependent of EO issue, achromatic liquid crystal EO devices are designed and demonstrated with a twisted-vertical alignment (TVA) configuration. While the original TVA mode was reported in 1993, the bottleneck of long response time resulting from degeneracy of tilt angle and defect annihilation during switch-on process stopped the new liquid crystal mode from becoming applicable to emerging devices. A polymer stabilization approach is proposed and experimentally demonstrated to command the homeotropic-to-twist transition for fast response time. Under optimum polymerization conditions, an 83% improvement in response time is achieved while attaining a high contrast ratio of 1300:1. The aligning effect contributed by the polymer structure is validated through theoretical analysis and simulation, which is based on free-energy calculation in the liquid crystal and polymer composite system. The second part of dissertation is in search of applications beyond displays. With the advantage of suppressed wavelength dispersion, both liquid crystal lens and microlens array with TVA configuration are demonstrated to have electrically-tunable focal length and reduced chromatic aberration. Both liquid crystal lenses show the merits of low-operation voltages of tunable focal length and both positive and negative lens power. We envision that this work will open new pathways to explore innovative optical and photonic devices.
Liang-Chy Chien, Dr. (Committee Chair)
Philip Bos, Dr. (Committee Member)
Antal Jakli, Dr. (Committee Member)
Elizabeth Mann, Dr. (Committee Member)
Michael Tubergen, Dr. (Committee Member)
178 p.
Physics
liquid crystal; chiral homeotropic; chromatic aberration; lens; microlens arrays; polymer

Recommended Citations

Citations

  • Chang, K.-H. (2018). Achromatic Liquid Crystal Electro-Optical Devices Based On a Twisted Vertical Alignment Configuration [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1523807996464507

    APA Style (7th edition)

  • Chang, Kai-Han. Achromatic Liquid Crystal Electro-Optical Devices Based On a Twisted Vertical Alignment Configuration. 2018. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1523807996464507.

    MLA Style (8th edition)

  • Chang, Kai-Han. "Achromatic Liquid Crystal Electro-Optical Devices Based On a Twisted Vertical Alignment Configuration." Doctoral dissertation, Kent State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1523807996464507

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Kent State University and OhioLINK.