Sub parts-per-billion detection of ethane in a 30-meters long mid-IR Antiresonant Hollow-Core Fiber

Abstract In this work, we present the first demonstration of a gas sensor utilizing the Wavelength Modulation Spectroscopy technique and a mid-IR guiding Antiresonant Hollow-Core Fiber with a record length of 30 m. The self-fabricated ARHCF was used as an air-tight, low-volume absorption cell delivering an extended laser-gas molecules interaction path within the sensor’s setup, which enabled it to efficiently detect ethane at 2996.88 cm−1. Benefiting from the unique guidance properties of the ARHCF, the sensor reached a minimum detection limit of 670 parts-per-trillion by volume for 14 s integration time, which is at a level comparable to the bulk optics-based systems utilizing more complex detection techniques or multipass cells with tens of meters long optical path lengths. The obtained results confirm that ARHCF-based gas sensors can successfully compete with or even outperform bulk optics-based mid-IR gas sensor configurations. The obtained results show the potential for the development of novel, low-volume, compact, and reliable types of gas detectors allowing precise analysis of various gaseous substances at their trace concentration level.