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fast-response liquid crystals for photonic and display applications

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Date Issued:
2013
Abstract/Description:
Liquid crystals (LCs) are attractive for many applications such as information displays, spatial light modulators, and adaptive optics because the optical properties of these devices are electrically tunable. For most display and photonic applications, response time is a critical parameter especially for spatial light modulators that requires at least 2? phase change. This problem gets more severe as the wavelength increases because a thicker LC layer is needed, which results in a slower response time. A typical E7 nematic liquid crystal cell with 2? phase change shows a response time longer than 100 ms at room temperature, which is too slow. Therefore, solutions for achieving fast response time are in high demand.In this dissertation, several approaches for achieving submillisecond response time are investigated. In Chapter 2, we begin by introducing dual frequency liquid crystals (DFLCs) which provide possibility to achieve submillisecond rise time and decay time. We developed a DFLC mixture with a record-high birefringence (?n=0.39 at ?=633nm) based on phenyl-tolane compounds, which exhibit a positive dielectric anisotropy (??) and modest dielectric relaxation frequency. In Chapter 3, a phase modulator with 4? phase change and 400 (&)#181;s average gray-to-gray response time is demonstrated using a sheared polymer network liquid crystal (SPNLC). This device exhibits a low scattering at ?=532 nm due to the employed material set and shearing technique. We also discuss the application of SPNLCs for 3D displays.In Chapter 4, we studied the temperature effect on the splay elastic constant of polymer network liquid crystal (PNLC). Due to the existence of polymer network, the temperature dependent splay elastic constant of the LC cell deviates from the model for nematic LCs. In Chapter 5, we focus on PNLC light modulators. This technology is attractive because it can achieve submillisecond response time while maintaining a large phase change. However, the light scattering loss caused by grain boundaries of liquid crystal multi-domains at voltage-on state hinders the widespread application of PNLCs. By optimizing liquid crystal host, polymer, and proper curing process, we successfully eliminate light scattering from short wave infrared region (1.55 ?m) to visible range. In Chapter 6, we introduce a reconfigurable fabrication technique of tunable liquid crystal devices. Based on this technique and our scattering-free PNLCs, we developed a series of fast switching LC devices such as LC prism, grating and lens. The application of this technology in 3D lenticular lens development is also discussed. This technique provides a great flexibility for designing and fabricating LC photonic devices with desired refractive index profile.
Title: fast-response liquid crystals for photonic and display applications.
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Name(s): Sun, Jie, Author
Wu, Shintson, Committee Chair
Likamwa, Patrick, Committee Member
Schoenfeld, Winston, Committee Member
Wu, Xinzhang, Committee Member
University of Central Florida, Degree Grantor
Type of Resource: text
Date Issued: 2013
Publisher: University of Central Florida
Language(s): English
Abstract/Description: Liquid crystals (LCs) are attractive for many applications such as information displays, spatial light modulators, and adaptive optics because the optical properties of these devices are electrically tunable. For most display and photonic applications, response time is a critical parameter especially for spatial light modulators that requires at least 2? phase change. This problem gets more severe as the wavelength increases because a thicker LC layer is needed, which results in a slower response time. A typical E7 nematic liquid crystal cell with 2? phase change shows a response time longer than 100 ms at room temperature, which is too slow. Therefore, solutions for achieving fast response time are in high demand.In this dissertation, several approaches for achieving submillisecond response time are investigated. In Chapter 2, we begin by introducing dual frequency liquid crystals (DFLCs) which provide possibility to achieve submillisecond rise time and decay time. We developed a DFLC mixture with a record-high birefringence (?n=0.39 at ?=633nm) based on phenyl-tolane compounds, which exhibit a positive dielectric anisotropy (??) and modest dielectric relaxation frequency. In Chapter 3, a phase modulator with 4? phase change and 400 (&)#181;s average gray-to-gray response time is demonstrated using a sheared polymer network liquid crystal (SPNLC). This device exhibits a low scattering at ?=532 nm due to the employed material set and shearing technique. We also discuss the application of SPNLCs for 3D displays.In Chapter 4, we studied the temperature effect on the splay elastic constant of polymer network liquid crystal (PNLC). Due to the existence of polymer network, the temperature dependent splay elastic constant of the LC cell deviates from the model for nematic LCs. In Chapter 5, we focus on PNLC light modulators. This technology is attractive because it can achieve submillisecond response time while maintaining a large phase change. However, the light scattering loss caused by grain boundaries of liquid crystal multi-domains at voltage-on state hinders the widespread application of PNLCs. By optimizing liquid crystal host, polymer, and proper curing process, we successfully eliminate light scattering from short wave infrared region (1.55 ?m) to visible range. In Chapter 6, we introduce a reconfigurable fabrication technique of tunable liquid crystal devices. Based on this technique and our scattering-free PNLCs, we developed a series of fast switching LC devices such as LC prism, grating and lens. The application of this technology in 3D lenticular lens development is also discussed. This technique provides a great flexibility for designing and fabricating LC photonic devices with desired refractive index profile.
Identifier: CFE0005063 (IID), ucf:49968 (fedora)
Note(s): 2013-12-01
Ph.D.
Optics and Photonics, Optics and Photonics
Doctoral
This record was generated from author submitted information.
Subject(s): optics -- liquid crystals
Persistent Link to This Record: http://purl.flvc.org/ucf/fd/CFE0005063
Restrictions on Access: campus 2018-12-15
Host Institution: UCF

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