{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/140851"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/140851","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Ultra-sensitive Mid-infrared Detection Using Phononic Crystal Resonator-based Oscillator","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Xi, Zichen"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Electrical Engineering","degree_department":"Electrical and Computer Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Shao, Linbo"],"committee_members":["Zhu, Yizheng","Lin, Zin"],"year":2025,"date_issued":"2025-12-01","date_published":"2025-12-01","updated_at":"2026-07-22T22:20:00Z","subjects":["Mid-infrared Detector","Surface Acoustic Wave Device","Phononic Crystal Oscillator","Metasurface Absorber"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/10919/140851","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Shao, Linbo"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Zhu, Yizheng","Lin, Zin"]},{"key":"dc:contributor.department","label":"Department","values":["Electrical and Computer Engineering"]},{"key":"dc:creator","label":"Author","values":["Xi, Zichen"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-01-16T14:38:05Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-01-16T14:38:05Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-12-01"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Mid-infrared Detector","Surface Acoustic Wave Device","Phononic Crystal Oscillator","Metasurface Absorber"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/140851"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Mid-infrared (MIR) light carries rich information about the world around us. It reveals the chemical makeup of gases and liquids, enables long-distance optical communication through the atmosphere, and forms the basis of many detection systems used in environmental monitoring, space exploration, and national security. However, today’s MIR detectors often require bulky cooling systems or struggle to sense weak signals, which limit their use in compact and portable technologies. In this thesis, I demonstrate MIR light detectors that work at room temperature and are small enough to fit onto a microchip. Instead of relying on conventional electronics, my device “listens” to how a tiny vibrating structure changes its tone when it absorbs MIR light. The surface of the device is patterned with a special absorber array that efficiently captures specific colors of MIR light. When the absorbed light slightly warms the device, its vibration frequency shifts due to the temperature change induced by the absorbed light. People can read out this frequency shift to learn how much MIR light reaching the device. This method allows the detector to sense extremely small amounts of light while staying fast and stable. Because my detector operates at room temperature and does not require any cooling system, and can be manufactured using scalable processes, this technology is well positioned for real-world applications. It can support environmental and chemical sensing by identifying molecular signatures, assist free-space optical communication by detecting mid-infrared signals outdoors and contribute to national defense through compact infrared surveillance and threat-warning systems. Its small size and low power consumption also make it attractive for future space missions, portable medical devices, and lightweight imaging systems. Together, these capabilities point toward a new class of practical infrared detectors that combine sensitivity, speed, and robustness in a single miniature platform."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Ultra-sensitive Mid-infrared Detection Using Phononic Crystal Resonator-based Oscillator"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Shao, Linbo"],"dc:contributor.committeemember":["Zhu, Yizheng","Lin, Zin"],"dc:contributor.department":["Electrical and Computer Engineering"],"dc:creator":["Xi, Zichen"],"dc:date.accessioned":["2026-01-16T14:38:05Z"],"dc:date.available":["2026-01-16T14:38:05Z"],"dc:date.issued":["2025-12-01"],"dc:description.abstract":["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."],"dc:description.abstractgeneral":["Mid-infrared (MIR) light carries rich information about the world around us. It reveals the chemical makeup of gases and liquids, enables long-distance optical communication through the atmosphere, and forms the basis of many detection systems used in environmental monitoring, space exploration, and national security. However, today’s MIR detectors often require bulky cooling systems or struggle to sense weak signals, which limit their use in compact and portable technologies. In this thesis, I demonstrate MIR light detectors that work at room temperature and are small enough to fit onto a microchip. Instead of relying on conventional electronics, my device “listens” to how a tiny vibrating structure changes its tone when it absorbs MIR light. The surface of the device is patterned with a special absorber array that efficiently captures specific colors of MIR light. When the absorbed light slightly warms the device, its vibration frequency shifts due to the temperature change induced by the absorbed light. People can read out this frequency shift to learn how much MIR light reaching the device. This method allows the detector to sense extremely small amounts of light while staying fast and stable. Because my detector operates at room temperature and does not require any cooling system, and can be manufactured using scalable processes, this technology is well positioned for real-world applications. It can support environmental and chemical sensing by identifying molecular signatures, assist free-space optical communication by detecting mid-infrared signals outdoors and contribute to national defense through compact infrared surveillance and threat-warning systems. Its small size and low power consumption also make it attractive for future space missions, portable medical devices, and lightweight imaging systems. Together, these capabilities point toward a new class of practical infrared detectors that combine sensitivity, speed, and robustness in a single miniature platform."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["https://hdl.handle.net/10919/140851"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Mid-infrared Detector","Surface Acoustic Wave Device","Phononic Crystal Oscillator","Metasurface Absorber"],"dc:title":["Ultra-sensitive Mid-infrared Detection Using Phononic Crystal Resonator-based Oscillator"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Electrical Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:20:00Z"}