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Nested Ring Resonant Sagnac-Enhanced Photothermal Gas Sensing Using a Nanofiber
Fu Wan1, Lei Zhu1, Yaotian Bai1
1State Key Laboratory of Power Transmission Equipment Technology, School of Electrical Engineering, Chongqing University, Chongqing 400044, China.
Analytical Chemistry
|March 5, 2026
Summary
A novel nested ring resonant Sagnac-enhanced photothermal (PT) gas sensor achieves high sensitivity and fast response for trace gas detection. This PT sensor offers practical usability for remote monitoring applications.
Area of Science:
- Optics and Spectroscopy
- Chemical Sensing
- Nanotechnology
Background:
- Photothermal (PT) spectroscopy offers high sensitivity and selectivity for trace gas detection.
- Developing PT gas sensors with fast response, high sensitivity, and practical usability is challenging.
Purpose of the Study:
- To demonstrate a nested ring resonant Sagnac-enhanced PT gas sensor using a nanofiber.
- To improve sensitivity and response time for trace gas detection.
Main Methods:
- Utilizing a nested ring resonator within a Sagnac loop to enhance cavity finesse.
- Employing a nanofiber for PT phase modulation.
- Achieving acetylene (C2H2) detection with a 2 cm nanofiber and resonator finesse of 73.
Main Results:
- Achieved a noise equivalent concentration of 16 ppb for C2H2 detection.
- Demonstrated a response time of 19 s and <3% instability over 2 h.
- Improved sensitivity by a factor of 10 compared to a nonresonant Sagnac interferometer.
Conclusions:
- The nested ring resonant Sagnac-enhanced PT sensor successfully integrates fast response and high sensitivity.
- The sensor design simplifies operation, making it suitable for remote monitoring and distributed sensing.
