Development of a gas-phase Raman instrument using a hollow core anti-resonant tubular fibre

Versatile and flexible gas analysis for compositional identification and quantification is a demand found in a variety of diverse sectors. As such, a compact, deployable instrument exhibiting both high specificity and sensitivity is a highly attractive proposition for a wide range of applications. In this paper, we describe a gas phase Raman spectroscopy-based device using state-of-the-art anti-resonant (tubular) hollow core micro-structured optical fibre (HC-MOF). This fibre architecture allows the use of lengths that are typically longer than have been demonstrated previously, allowing substantially enhanced interaction lengths between the pump laser and the gas sample to be achieved, addressing the sensitivity challenges typically observed in gas-phase Raman measurements and enabling application for remote sensing in hazardous environments. We describe the successful development of a compact, fibre-integrated instrument and present results obtained during a test campaign at an industrial laboratory; marking a milestone in gas-phase Raman spectroscopy. The unique properties of the MOF used allowed a 20-m length to be utilised, representing a new record length for gas phase Raman measurements. The identification and quantification of a variety of gas species, ranging from simple homonuclear diatomic gases to heteronuclear organic gas species were achieved, and, building on previous studies, the instruments stability, gas concentration linearity response, and the hollow core fibre filling and purging characteristics were investigated.

Automated summary

The article describes a new development in gas analysis using gas phase Raman spectroscopy, achieving longer interaction lengths and improved sensitivity by using specially designed hollow core micro-structured optical fiber. The successful development of a compact, fiber-integrated instrument enables the identification and quantification of various gas species, with broad application prospects.