All-Fiber Multicomponent Gas Raman Probe Based on Platinum-Coated Capillary Enhanced Raman Spectroscopy

This paper presents a compact all-fiber multicomponent gas Raman probe using a dual-fiber architecture within a platinum-coated capillary. The probe eliminates the need for conventional optical components like filters and dichroic mirrors by strategically employing metal coating on the excitation fiber's surface to suppress interference signals. A detailed analysis of the silica Raman signal and fluorescence propagation within the system facilitated this design. Metal-coated capillary (MCC), produced via atomic layer deposition (ALD) of platinum on silica capillaries, exhibits excellent optical properties and environmental resilience, boosting gas Raman signal reception. Careful alignment of the dual fibers relative to the platinum-coated capillary optimizes signal-to-noise ratio enhancement. The system achieves detection limits of 21 ppm for CH₄, 30 ppm for C₂H₄, and 51 ppm for C₂H₆ within 45 s of exposure, alongside a rapid response time of 25 s (relative to systems based on hollow-core antiresonant fibers) and robust stability. Its streamlined optical path and compact design enhance practicality across diverse fields, including agriculture, industry, environmental monitoring, and healthcare, advancing multicomponent gas detection technology.