Optical Fiber Photoacoustic Gas Sensor With Graphene Nano-Mechanical Resonator as the Acoustic Detector

• Published in: IEEE journal of selected topics in quantum electronics Vol. 23; no. 2; pp. 199 - 209
• Main Authors: Tan, Yanzhen, Zhang, Congzhe, Jin, Wei, Yang, Fan, Lut Ho, Hoi, Ma, Jun
• Format: Journal Article
• Language: English
• Published: IEEE 01.03.2017
• Subjects: Acoustics; Detectors; Gas sensor; Graphene; Laser excitation; multilayer graphene; nano-mechanical resonator; optical fiber sensor; Optical fiber sensors; Optical fibers; Optical resonators; photoacoustic spectroscopy
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2016.2606339

We report an all-optical fiber photoacoustic gas sensor with a graphene nano-mechanical resonator as the acoustic detector. The acoustic detector is a Fabry-Perot interferometer formed by attaching a 100-nm-thick, 2.5-mm-diameter multilayer graphene diaphragm to a hollow cavity at the end of a single-mode optical fiber. By operating at one of the mechanical resonances of the diaphragm, the sensitivity for acoustic detection is enhanced and a noise equivalent minimum detectable pressure of 2.11 μPa/Hz 1/2 at 10.1 kHz is demonstrated. Detection of acetylene gas is demonstrated with a distributed feedback semiconductor laser tuned to the P(9) absorption line of acetylene and a lower detection limit of 119.8 parts-per-billion (ppb) is achieved with 123.9-mW pump power. Theoretical analysis shows that by increasing the Q-factor of the resonator, which may be achieved by operating at low gas pressures, ppb level gas detection is possible. The all-fiber photoacoustic gas sensor is immune to electromagnetic interference, safe in flammable and explosive environment, and would be ideally suited for remote, space-limited applications and for multipoint detection in a multiplexed fiber optic sensor network.