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Reconfigurable Metasurfaces in Nanoelectromechanical and Silicon-Organic Systems


Zheng, Tianzhe (2024) Reconfigurable Metasurfaces in Nanoelectromechanical and Silicon-Organic Systems. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2kmq-da15.


Over the past decade, metasurfaces, a technology referring to 2D or 3D engineered nanostructures, has demonstrated itself as a groundbreaking solution for creating compact and multifunctional optical devices. Moreover, the integration of metasurfaces with various modulation techniques enables compact yet high-performance active optical systems. In this thesis I explore various optical modes in engineered nanostructures and apply different design techniques to improve the amplitude and phase response of free-space modulators.

In Chapter 1 and 2, we first briefly introduce the concept of reconfigurable metasurfaces and its state of art. Then we introduce several nanophotonic concepts that will be used frequently in later projects and discuss the potential directions to improve modulator's performance.

In Chapter 3, we find that the dual-mode resonant metasurfaces could improve the phase response in the nanoelectromechanical system(NEMS). The interaction between the quasi-bond state in the continuum and guided mode resonance boosts the phase response up to 144 degrees.

In Chapter 4, the design target is to utilize the high-Q mode to decrease the driving voltage of the NEMS system to CMOS level. Motivated by the low-index confinement property of the slot mode, the device achieves over 10% reflection amplitude modulation with only 1.5V in the experiment. In addition, by adding a bottom gold mirror, 1.8π phase response is numerically observed. Based on the success of this device, we propose a design that could achieve subwavelength wavefront control. As a example, we show a 3-pixel optical beam deflector with 75% diffraction efficiency.

In Chapter 5, we extend the use of the slot mode into silicon-organic hybrid devices. The utilization of the slot mode achieves efficient electro-optic tuning under 17V in free space with a MHz modulation speed. We also explored various methods to enhance its phase response and discuss its feasibility. The spatial phase modulation design is also proposed with a 12-period supercell pixel. The beam deflector achieves 70% diffraction efficiency numerically.

In Chapter 6, we bring this dissertation to a close and outline potential directions for future research.

This thesis provides a foundation for the development of high-resolution and power-efficient one-dimensional spatial light modulators and showcases the potential of reconfigurable metasurfaces.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Metasurface; Nanophotonics; Nanofabrication; Spatial light modulator;Reconfigurable deivce;Optics;NEMS;Electro-optic polymer;Electro-optic device;
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Faraon, Andrei
Group:Kavli Nanoscience Institute
Thesis Committee:
  • Vahala, Kerry (chair)
  • Faraon, Andrei
  • Marandi, Alireza
  • Scherer, Axel
Defense Date:23 January 2024
Funding AgencyGrant Number
National Institutes of Health (NIH)R21EY029460-01
Army Research Office (ARO)W911NF2210097.
Caltech Sensing to Intelligence (S2I)UNSPECIFIED
Record Number:CaltechTHESIS:03062024-043923772
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Chapter 3 adapted for Chapter 4 adapted for Chapter 5
Zheng, Tianzhe0000-0001-7058-5196
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16317
Deposited By: Tianzhe Zheng
Deposited On:16 Apr 2024 18:10
Last Modified:29 Apr 2024 18:25

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