Mid-infrared photoacoustic gas monitoring driven by a gas-filled hollow-core fiber laser

Abstract

Development of novel mid-infrared (MIR) lasers could ultimately boost emerging detection technologies towards innovative spectroscopic and imaging solutions. Photoacoustic (PA) modality has been heralded for years as one of the most powerful detection tools enabling high signal-to-noise ratio analysis. Here, we demonstrate a novel, compact and sensitive MIR-PA system for carbon dioxide (CO2) monitoring at its strongest absorption band by combining a gas-filled fiber laser and PA technology. Specifically, the PA signals were excited by a custom-made hydrogen (H2) based MIR Raman fiber laser source with a pulse energy of ⁓ 18 μJ, quantum efficiency of ⁓ 80% and peak power of ⁓ 3.9 kW. A CO2 detection limit of 605 ppbv was attained from the Allan deviation. This work constitutes an alternative method for advanced high-sensitivity gas detection.

A Review: Application and Implementation of Optic Fibre Sensors for Gas Detection

“…There has been a significant increase of spectroscopic techniques for the detection of carbon dioxide [111][112][113]. The principal absorption wavelengths are in the near and mid infrared, as follows: spectrum bands of lines are at ~2.005 µm (R branch), ~2.015 µm (P branch) [113] with absorption lines in the mid-infrared at ~4.2 µm [111,112] and ~2.6 µm [111]. There are some interference issues due to water vapour absorption lines in the range 2 µm and 6 µm causing cross-talk in the sensitivity and selectivity.…”

“…A number of MOS devices have LODs from 0.02% to 0.1%, but require 100 s of degrees centigrade to operate [183], which is an issue for sustained periods of standalone remote sensing. Recent published data on MOS sensors suggest ~0.2% to 1%, though still requiring elevated temperatures [112,113,116,123,181]. All optical fibre devices operate at room temperature.…”

“…Spectroscopic sensors have good performances, but are very much lab-based schemes with the potential to be used in-situ [116,181] as well as for environmental applications and [115,117,123] with largest range of operation, but they still have LOD and resolution problems. Scrutinising the performances and comparing them to each other, spectroscopic sensors using cavities, either PCF or intra-cavity, yield the best LODs [112,113] but have slow response times, although this is not critical for atmospheric measurement of CO 2 . The reaction and absorption spectra given by NiO/rGO coatings [116] yield similar results to spectroscopic sensors but with a faster response over the same concentration ranges.…”

“…The reaction and absorption spectra given by NiO/rGO coatings [116] yield similar results to spectroscopic sensors but with a faster response over the same concentration ranges. Another point of concern with cavity sensors [112,113,187,188] is that they need additional apparatus to deliver the gas sample into the cavities, either via vacuum or high pressure, which is not needed for reactive coatings, such as NiO/rGO [116] or FOM [123,189]. Furthermore, for industrial monitoring applications of control processes, all sensors operate over a wider range, and have relatively slow response times [114,115,117,122,123].…”

Acoustic Optical Fiber Sensor Based on Graphene Oxide Membrane

“…Optical fiber sensors for acoustic waves detection is based in different mechanisms including photoacoustics [13], with special interest in the biomedical field [14,15], interferometry [16,17], among other [18][19][20]. In particular, interferometry-based sensors have found many research interests due to the compact size and simple fabrication.…”