Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


Volodymyr_Borshch_Dissertation_final.pdf (4.8 MB)

ETD Abstract Container

Abstract Header

Nanosecond Electric Modification of Order Parameters

Borshch, Volodymyr
http://rave.ohiolink.edu/etdc/view?acc_num=kent1416443341

Abstract Details

2014, PHD, Kent State University, College of Arts and Sciences / Chemical Physics.
In this Dissertation, we study a nanosecond electro-optic response of a nematic liquid crystal in a geometry where an applied electric field E modifies the tensor order parameter but does not change the orientation of the optic axis (director N̂). We use nematics with negative dielectric anisotropy with the electric field applied perpendicularly to N̂. The field changes the dielectric tensor at optical frequencies (optic tensor), due to the following mechanisms: (a) nanosecond creation of biaxial orientational order; (b) uniaxial modification of the orientational order that occurs over the timescales of tens of nanoseconds, and (c) quenching of director fluctuations with a wide range of characteristic times up to milliseconds. We develop a model to describe the dynamics of all three mechanisms. We design the experimental conditions to selectively suppress the contributions from the quenching of director fluctuations (c) and from the biaxial order effect (a) and thus, separate the contributions of the three mechanisms in the electro-optic response. As a result, the experimental data can be well fitted with the model parameters. The analysis provides a rather detailed physical picture of how the liquid crystal responds to a strong electric field, E ~ 108 V/m, on a timescale of nanoseconds. This work provides a useful guide in the current search of the biaxial nematic phase. Namely, the temperature dependence of the biaxial susceptibility allows one to estimate the temperature of the potential uniaxial-to-biaxial phase transition. An analysis of the quenching of director fluctuations indicates that on a timescale of nanoseconds, the classic model with constant viscoelastic material parameters might reach its limit of validity. The effect of nanosecond electric modification of the order parameter (NEMOP) can be used in applications in which one needs to achieve ultrafast (nanosecond) changes of optical characteristics, such as birefringence.
Oleg Lavrentovich, DSc (Advisor)
Sergij Shiyanovskii, DSc (Advisor)
120 p.
Condensed Matter Physics; Experiments; Materials Science; Optics; Physics
Liquid Crystals; electro-optics; nanoseconds; Liquid Crystal Displays; dielectric anisotropy; nematic; dynamics; ultrafast switching; soft matter; uniaxial; biaxial; order parameter; fluctuations; birefringence;

Recommended Citations

Citations

  • Borshch, V. (2014). Nanosecond Electric Modification of Order Parameters [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1416443341

    APA Style (7th edition)

  • Borshch, Volodymyr. Nanosecond Electric Modification of Order Parameters. 2014. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1416443341.

    MLA Style (8th edition)

  • Borshch, Volodymyr. "Nanosecond Electric Modification of Order Parameters." Doctoral dissertation, Kent State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1416443341

    Chicago Manual of Style (17th edition)

kent1416443341
802
© 2014, some rights reserved.Creative Commons License Nanosecond Electric Modification of Order Parameters by Volodymyr Borshch is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Kent State University and OhioLINK.