Coaxially nested component with asymmetric fiber resonant cavity and separation membrane for gaseous and dissolved...

Dynamically, simultaneously and sensitively embedded or external detection of multi-component gaseous or dissolved phase gases in millilitre volumes is critical for many frontier applications. Raman spectroscopy based on a single-wavelength laser can achieve simultaneous detection of various gases (except noble gases), but it lacks sensitivity. Therefore, this paper firstly develops a theoretical framework for Raman signal generation within the fiber resonant cavity (FRC), and based on which, an asymmetric FRC is proposed to balance the laser power enhancement and the intracavity loss caused by a high-reflectivity input cavity mirror, enhancing the Raman signal intensity by 170 times when compared to only hollow-core fiber and 36 times to only geometry resonant cavity, achieving sensitive gas detection with a limit of detection (LOD) as low as 0.01 ppm*bar. Meanwhile, a coaxially nested component with FRC and separation membrane is proposed, which can enable approximate synchronization of liquid-gas separation and detection. This work provides an effective solution of measurement instruments to realize d high-precision detection of multi component gases in various states with gas consumption ranging from 0.3 mL to 2 mL, enabling further refinement of the associated generation and decomposition pathways of different gases, and the coaxially nested component also can be used in other scattering-based spectroscopic techniques (e.g., Brillouin spectroscopy) and absorption-based spectroscopic techniques.