Next Generation Phase-only LCOS Device with Ultra-low Phase Flicker for Holographic Applications

Phase-only LCOS devices have become one of the most promising optical engines for digital holographic applications. However, the system performance can be degraded by the instability of the phase levels, i.e., the so-called phase flicker. For instance, a large phase flicker means a low spatial information bandwidth for holographic 3D displays, high device level crosstalk for wavelength selective switches, or low trap stability of single atoms for holographic optical tweezers. This research aims to develop next generation digitally-driven phase-only LCOS devices with ultra-low phase flicker. The work begins with the design and construction of a fully automated characterization system for phase-only LCOS devices. The system can be operated in either diffractive mode or polarimetric mode and is able to precisely measure the phase performance of LCOS devices. Based on the measurement results, the impacts of phase flicker on fundamental multilevel phase elements, in terms of blazed grating and image hologram, are quantitatively simulated and are shown to be comparable to that introduced by phase quantization and amplitude noise, respectively. Two methods are proposed and investigated to minimize the phase flicker by optimizing the digital driving waveforms of the LCOS device. The first one is based on a strategy of splitting selected long pulses and distributing them in a uniform manner, enabling a meaningful increase of phase levels from 8 bits to 9 bits. However, this method is based on manual selection for individual LCOS devices, which is not easy to apply in general. The second method overcomes this problem. It is based on a deep learning model built with fully connected layers, making it possible to practically realize 10-bit phase modulation for digitally-driven LCOS devices. Finally, a comprehensive technical guideline for phase flicker optimization is provided, in terms of the clock frequency of the LCOS backplane circuit and the LC viscosity, to help the end-users gain a better understanding and improve the phase resolution of the LCOS devices to optimum for their desired applications.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2021

Author dc:creator

• Tong, Yuan

Advisor dc:contributor.advisor

• Chu, Daping

• Digital Holography
• Spatial Light Modulator
• Liquid-Crystal Devices

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/7b9087c1-1581-4943-9756-312e80922c92/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

Author Identifier

0000-0002-9710-7386

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/325091