Methane Gas Photonic Sensor Based on Resonant Coupled Cavities

Area of Science:

• Photonics
• Gas Sensing
• Optical Sensors

Background:

• Methane gas detection is critical for safety and environmental monitoring.
• Existing sensors may face limitations in sensitivity, cost, or self-referencing capabilities.

Purpose of the Study:

• To develop a cost-effective photonic sensor for methane gas detection.
• To utilize absorption-induced light redirection in coupled resonant cavities for sensing.
• To achieve a self-referenced readout immune to source power fluctuations.

Main Methods:

• Implemented a sensor architecture with a Fabry-Pérot (FP) resonator coupled to a fiber ring resonator.
• Exploited the change in FP absorption coefficient with methane concentration.
• Analyzed the ratio of counter-propagating resonant modes in the fiber ring resonator for readout.

Main Results:

• Demonstrated methane concentration evaluation via resonant mode power ratios.
• Achieved a sensitivity of 0.37 ± 0.04 [dB/%] for methane concentrations from 0% to 5%.
• Reached a detection limit below the lower explosive limit (LEL).

Conclusions:

• The developed photonic sensor offers a cost-effective solution for methane detection.
• The self-referenced readout scheme enhances reliability by mitigating source power variations.
• The sensor's sensitivity and low detection limit are suitable for safety-critical applications.