Non-reciprocity in piezoelectric and electrostatic microelectromechanical systems

Zhao, Jianing

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https://hdl.handle.net/2142/120560 Copy

Description

Title

Non-reciprocity in piezoelectric and electrostatic microelectromechanical systems

Author(s)

Zhao, Jianing

Issue Date

2023-04-28

Director of Research (if dissertation) or Advisor (if thesis)

Bahl, Gaurav

Doctoral Committee Chair(s)

Bahl, Gaurav

Committee Member(s)

• von der Zande, Arend
• Tawfick, Sameh
• Fang, Kejie

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Non-reciprocity
• Piezoelectric
• Electrostatic
• Microelectromechanical systems (MEMS)
• Spatiotemporal Modulation

Abstract

Reciprocity requires that the transmission of energy is symmetric during forward and backward wave propagation between two ports inside a material. Non-reciprocal devices, such as isolator, circulator and gyrator, are important components for manipulation and routing of signals. Application examples of non-reciprocal devices include simultaneous-transmit-and-receive (STAR) radar in state-of-the-art telecommunication systems, and noise isolation through different amplifier stages in quantum computers. Conventional non-reciprocal devices based on Faraday effect require magnetooptic materials, which are bulky, expensive and not compatible with integratedcircuits based electronic systems fabricated by modern semiconductor process. Microscale acoustic devices (such as microelectromechanical systems or MEMS) benefit smaller footprint due to the shorter acoustic wavelength, and serve as advantageous alternatives in front-end radio-frequency applications such as filters and resonators. However, there are few approaches available to make these microscale acoustic devices nonreciprocal at the mechanics level. There are grant challenges to realize non-reciprocal acoustic propagation without using of magnetic materials and making the device fabrication compatible with advanced manufacturing processes used in integrated circuits. In this research work, we present an experimental demonstration of a micro-scale non-reciprocal piezoelectric acoustic resonator system by spatiotemporal modulation. We demonstrate an isolator behaviour based on coupled piezoelectric resonators chain and the spatiotemporal modulation generates non-reciprocal transmission through the synthetic Hall effect for phonon. Frequency modulation is realized by shunting time-varying electric circuitry to piezoelectric resonator due to electromechanical coupling. Next, instead of coupling physically separate resonators, we take advantage of a typical electrostatic MEMS gyroscope resonator which supports two degenerated eigenmodes and demonstrate non-reciprocal admittance responses by the spatiotemporal modulation method. Our experimental results show high non-reciprocal contrast ratio because of strong modulation from electrostatic forces. This result is among the largest demonstrations of nonreciprocal MEMS including hybrid electronics-MEMS, acoustoelectric effect, breaking parity-time symmetry, and piezoelectric nonlinear stiffening. In addition, we extend the concept of spatiotemporal modulation to electrostatic coupling strengths instead of resonance frequency of piezoelectric resonator, and experimentally demonstrate an electrostatic gyrator on a MEMS tuning fork resonator. This method can be generalized to optimize other figure of merit for gyrator, such as bandwidth and insertion loss, by replacing a resonator to linear waveguide or cascaded resonator filters. Finally, we propose a design of circulator device by extending the idea of coupled resonator chain system and verify the directional signal flow inside the closed resonator loop by the numerical simulation of coupled mode theory. Furthermore, we reconfigure the coupled resonator chain devices to propose a design of gyration behavior when the strong modulation depth excites the mode splitting of higher order side-bands. iii

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Jianing Zhao

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