Fiber-Optic Photoacoustic Gas Microprobe Based on Linear Spot-Type Multipass Cell

Area of Science:

• Optoelectronics
• Gas Sensing Technology
• Spectroscopy

Background:

• Traditional photoacoustic gas sensors often suffer from large volumes and weak signal intensity.
• Enhancing sensitivity and miniaturization are key challenges in developing advanced gas detection systems.

Purpose of the Study:

• To develop a highly sensitive and miniaturized fiber-optic photoacoustic gas microprobe.
• To improve photoacoustic signal intensity and reduce gas chamber volume through innovative design.

Main Methods:

• A linear spot-type multipass cell was integrated into a fiber-optic photoacoustic microprobe.
• The photoacoustic tube's cross-section was designed as a slit (10 mm height, 1.5 mm width) to reduce volume (210 μL) and enhance signal.
• A cantilever beam formed a Fabry-Perot interferometer with an optical fiber for enhanced detection, utilizing 26 light passes.

Main Results:

• The slit cross-section design increased photoacoustic intensity over 6 times compared to traditional circular designs.
• Multipass reflections (13 spots) amplified the photoacoustic signal by 12.4 times versus a single reflection.
• The sensor achieved a 1.5 ppb detection limit for acetylene gas with a 400 s averaging time.

Conclusions:

• The proposed fiber-optic photoacoustic gas microprobe offers a significant advancement in gas sensing technology.
• The slit-shaped cell and multipass configuration effectively enhance sensitivity and reduce sensor size.
• This technology holds promise for sensitive and precise gas detection applications.