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Hollow Waveguide Multipass Cavity Enhanced Raman Spectroscopy for Trace Gases Sensing
Miaolin Wang1,2, Pinyi Wang1,2, Jianxin Wang1,2
1State Key Laboratory of Power Transmission Equipment Technology, Chongqing University, Chongqing 400044, China.
Analytical Chemistry
|November 5, 2025
Summary
A novel hollow waveguide multipass cavity (HMC) significantly enhances Raman spectroscopy for trace gas detection. This technology improves signal collection, enabling sensitive detection of gases like methane and hydrogen.
Area of Science:
- Optics and Photonics
- Spectroscopy
- Environmental Science
Background:
- Raman spectroscopy is a powerful tool for chemical analysis.
- Enhancing Raman signal collection is crucial for detecting trace gases.
- Hollow waveguides offer potential for improved light-gas interaction.
Purpose of the Study:
- To develop and evaluate a hollow waveguide multipass cavity (HMC) for enhanced Raman spectroscopy.
- To improve the sensitivity and detection limits for trace gas analysis.
- To demonstrate the HMC's capability for multigas detection.
Main Methods:
- Fabrication of a hollow waveguide coated with multilayer dielectric films.
- Integration of the waveguide into a multipass cavity design for 50 laser reflections.
- Simulation of intracavity beam reflection behavior.
- Experimental measurement of Raman spectra for ambient air, methane (CH4), and hydrogen (H2).
Main Results:
- The HMC design significantly enhances Raman signal collection.
- Achieved limits of detection of 0.87 ppm for CH4 and 2.06 ppm for H2.
- Demonstrated sensitive detection of multiple gases simultaneously.
- Calculated variations between output Raman signal intensity and HMC parameters.
Conclusions:
- The HMC is a highly effective system for enhancing Raman spectroscopy sensitivity.
- This approach shows great promise for advanced gas sensing applications.
- The HMC technology enables sensitive and selective detection of trace gases.
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