All-fiber hollow-core fiber gas cell

We present a hollow-core fiber (HCF) gas cell with light launched and collected via standard solid-glass core single-mode fibers (SMFs). Gas delivery is realized via a 100 mu m gap between the SMF and HCF with light low-loss coupling optimized for such a gap. Coupling into higher-order modes as well as the Fresnel reflections at the SMF-HCF interface are strongly suppressed to minimize unwanted multi-path interference. The assembled HCF gas cell including the gas inlet is encapsulated in a conventional metallic T-piece for easy gas filling, venting, and sealing. Thanks to its numerous features, such as alignment-free design (once fabricated), above-described promising optical performance, and compactness, we believe it will be of interest for applications in gas sensing and as gas references.