All-fiber offset-core sandwich-structured gas sensor based on photothermal spectroscopy detection

Area of Science:

• Optical Engineering
• Sensor Technology
• Gas Spectroscopy

Background:

• Fabry-Pérot (FP) interferometers are crucial optical components.
• Miniaturized FP sensors offer advantages in size and portability.
• Developing sensitive and stable gas detection systems remains a challenge.

Purpose of the Study:

• To present the first application of an all-fiber offset-core sandwich-structured Fabry-Pérot (OSFP) sensor for gas detection.
• To demonstrate the sensor's capability for ultra-compact, low-finesse FP cavity gas sensing.
• To achieve high-stability, low-limit detection of specific gases.

Main Methods:

• Fabrication of an ultra-compact OSFP sensor with a 150 μm cavity length and <1.4 nL volume.
• Implementation of photothermal wavelength modulation.
• Utilizing interferometric phase demodulation for signal processing.

Main Results:

• The OSFP sensor achieved a minimum detection limit of 390 ppb for acetylene (C₂H₂) gas.
• Demonstrated highly stable gas detection without complex feedback control.
• The sensor exhibits low detection limits, facile fabrication, and high stability.

Conclusions:

• The developed OSFP sensor represents a significant advancement in compact optical gas sensing.
• This technology holds promise for sensitive acetylene detection in various applications.
• Potential applications include medical testing and gas detection in harsh environments.