Gas detection with micro- and nano-engineered optical fibers

Abstract

a b s t r a c tThis paper overviews recent development in gas detection with micro-and nano-engineered optical fibers, including hollow-core fibers, suspended-core fibers, tapered optical micro/nano fibers, and fiber-tip micro-cavities. Both direct absorption and photoacoustic spectroscopy based detection schemes are discussed. Emphasis is placed on post-processing stock optical fibers to achieve better system performance. Our recent demonstration of distributed methane detection with a $75-m long of hollow-core photonic bandgap fiber is also reported.

Pulsed photothermal interferometry for spectroscopic gas detection with hollow-core optical fibre

“…However, the use of long HC-PBF would result in slow response due to time taking to fill the hollow-core. The response time may be reduced by introducing micro-channels along the HC-PBF or applying pressure differentials1. We have recently demonstrated the drilling of multiple low-loss micro-channels along a single HC-PBF with spacing between the micro-channels of a few cm, which would enable gas HC-PBF gas sensors with response time of well below 1 min320.…”

“…Compared with traditional electrochemical and semiconductor sensors, optical fibre sensors based on laser absorption spectroscopy offer good selectivity and sensitivity, with additional advantages such as capability for remote detection and immunity to electromagnetic interference. Earlier optical fibre gas sensors used micro-optic open-path cells and the sensitivity is limited due to the weak absorption of gases within the transmission windows of the standard (silica) optical fibres and the difficulty in building long path-length absorption cells with compact size1. The use of HC-PBF allows the construction of compact absorption gas cells with optical path length of many meters23.…”

Photonic sensors and devices based on hollow-core photonic bandgap fibres

“…Distributed gas detection is also possible by detecting loss distribution along the entire length of a HC-PBF with for example an optical time domain reflectometer [3]. Currently, the detection sensitivity (and stability) is limited by modal interference (MI) noise since the current commercial HC-PBFs support higher-order core/cladding modes which interfere with the fundamental mode and induce fluctuation in the transmitted light intensity.…”

Quartz Enhanced Photoacoustic Detection Based on an Elliptical Laser Beam

“…Trace gas detection techniques play an important role in the fields of environment, industry, aerospace, and medical technology [1][2][3][4][5]. Various optical sensing methods for atmospheric monitoring have been reported by numerous researchers [6][7][8][9][10]. Compared with other optical spectroscopic techniques, photoacoustic spectroscopy (PAS) technology is one of the most effective approaches for trace gas sensing, in which a microphone is employed to detect acoustic signals generated by the modulated optical radiation in a weakly absorbing gas [11][12][13].…”