Multichannel continuous-wave fiber cavity ringdown gas sensing utilizing frequency-shifted interferometry

Area of Science:

• Optical Sensing
• Spectroscopy
• Analytical Chemistry

Background:

• Conventional fiber cavity ringdown (FCRD) gas sensing relies on pulsed light sources and time-domain measurements.
• Existing methods can be complex and costly, limiting multichannel applications.
• There is a need for more efficient and sensitive gas detection techniques.

Purpose of the Study:

• To introduce a novel multichannel continuous-wave (CW) fiber cavity ringdown (FCRD) gas sensing method.
• To demonstrate the feasibility of using frequency-shifted interferometry (FSI) for spatial domain intensity decay measurements.
• To evaluate the performance of the proposed system for gas concentration detection.

Main Methods:

• Developed a multichannel CW-FCRD system integrating frequency-shifted interferometry (FSI).
• Measured gas concentration by analyzing intensity decay rates in the spatial domain across different cavities.
• Experimentally validated the system using acetylene gas in a two-channel setup (0%-1% concentration range).

Main Results:

• Established a linear relationship between acetylene concentration and absorption loss, proportional to intensity decay rate.
• Achieved high measurement resolutions of 3.871%/dB and 3.658%/dB.
• Demonstrated the system's capability for multichannel gas detection with high sensitivity and precision.

Conclusions:

• The proposed FSI-FCRD method offers a low-cost, high-sensitivity, high-precision, and stable alternative for multichannel gas sensing.
• This technique overcomes limitations of conventional time-domain FCRD methods.
• The system shows significant potential for various gas detection applications.