Signal enhancement and noise suppression technologies in Raman spectroscopic gas sensing

Raman spectroscopy, which enables simultaneous detection of multi-gas components, is considered a valuable tool for gas analysis. However, the weak Raman scattering effect limits its application in the field of high-sensitivity gas detection. In this article, we summarize the principles and characteristics of existing techniques for improving the detection of Raman spectra, from both the perspectives of signal enhancement and noise suppression. Regarding signal enhancement techniques, the main methods include multi-pass cavity enhancement, resonant cavity enhancement, and hollow-core fiber enhancement. As for noise suppression methods, the primary approaches include spatial filtering, shifted excitation Raman difference spectroscopy, polarized Raman spectroscopy, and internal standard correction. Finally, we present and outlook on how to further enhance the sensitivity of Raman spectroscopy based on existing techniques, which can lay the foundation for the future development of robust and easy-to-use gas analysis instruments.