Shen, Dezhi;
(2025)
Modelling of liquid crystal devices.
Doctoral thesis (Ph.D), UCL (University College London).
Preview |
Text
PhD_thesis_DezhiShen_final.pdf - Accepted Version Download (6MB) | Preview |
Abstract
This thesis presents the advancement of modelling techniques for liquid crystal (LC) devices, focusing on the optical behaviour, defect management, and optimisation of device performance. The research introduces a finite difference frequency domain (FDFD) method that enables electromagnetic modelling. A significant portion of the work is dedicated to addressing the challenges posed by defects in LC devices, which often lead to performance degradation. The study develops methods to increase the threshold voltage for defect formation by reducing fringing field effects and analyses the impact of rubbing direction and electrode patterns on defect behaviour. Furthermore, the thesis explores the relationship between steady-state time and defect formation, presenting techniques to accelerate the steady-state and switching time using high voltage pulses. A novel approach is proposed, utilizing LC defects to create an abrupt phase change region in LC cell, leading to improved phase response in optical applications. This idea is demonstrated through the design and analysis of a reconfigurable phase blazed phase grating, showing enhanced performance in both transmission and reflection scenarios. Additionally, the concept of a phase front element (PFE) is introduced for holographic display applications, featuring a new liquid crystal on silicon (LCOS) architecture design with a reduced 2 µm pixel pitch that improves field of view (FoV) to 15.8°, reduces crosstalk through optimised electrode patterns and implementation of the negative dielectric anisotropy LC material. The thesis also enhances the Gerchberg-Saxton algorithm to accommodate the non-uniform wavefronts generated by the pixels of PFE, resulting in superior hologram generation.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Modelling of liquid crystal devices |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10206104 |
Archive Staff Only
 |
View Item |
