Ultra-sensitive Mid-infrared Detection Using Phononic Crystal Resonator-based Oscillator

Mid-infrared (MIR) detection is essential for many applications such as chemical sensing, communications, space explorations, and national defense. Existing MIR detectors are typically categorized into two major classes: (1) semiconductor photodetectors, which offer high responsivity and fast response time but typically require cryogenic cooling, and (2) thermal-based sensors, which can operate at room temperature but suffer from low sensitivity and slow response times. In this thesis, I demonstrate room-temperature MIR detectors based on surface acoustic wave (SAW) phononic crystal (PnC) oscillators. By configuring a PnC resonator featuring high-frequency-quality-factor product into a low-noise self-oscillation system, my MIR detector achieves high sensitivity on the order of hundreds of picowatts. The SAW architecture also provides significantly higher thermal conductance than suspended thin-film structures, enabling fast thermal response. Overall, this work demonstrates a room-temperature MIR detection approach that combines high sensitivity with rapid thermal response through SAW PnC engineering, offering a pathway toward broadly applicable MIR sensing, spectroscopy, and communication technologies.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Electrical Engineering

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2025

Author dc:creator

• Xi, Zichen

Chair dc:contributor.committeechair

• Shao, Linbo

Committee members dc:contributor.committeemember

• Zhu, Yizheng
• Lin, Zin

• Mid-infrared Detector
• Surface Acoustic Wave Device
• Phononic Crystal Oscillator
• Metasurface Absorber

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10919/140851

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/140851