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Indexed by:Journal Papers

Date of Publication:2019-12-01

Journal:PHOTONIC SENSORS

Included Journals:SCIE、EI

Volume:9

Issue:4

Page Number:293-301

ISSN No.:1674-9251

Key Words:Trace gas detection; photoacoustic spectroscopy; cantilever microphone; fiber-optic Fabry-Perot interferometer; near-infrared laser

Abstract:A trace ammonia (NH3) detection system based on the near-infrared fiber-optic cantilever-enhanced photoacoustic spectroscopy (CEPAS) is proposed. A fiber-optic extrinsic Fabry-Perot interferometer (EFPI) based cantilever microphone has been designed to detect the photoacoustic pressure signal. The microphone has many advantages, such as small size and high sensitivity. A near-infrared tunable erbium-doped fiber laser (EDFL) amplified by an erbium-doped fiber amplifier (EDFA) is used as a photoacoustic excitation light source. To improve the sensitivity, the photoacoustic signal is enhanced by a photoacoustic cell with a resonant frequency of 1624 Hz. When the wavelength modulation spectroscopy (WMS) technique is applied, the weak photoacoustic signal is detected by the second-harmonic detection technique. Trace NH3 measurement experiments demonstrate that the designed fiber-optic CEPAS system has a linear response to concentrations in the range of 0 ppm - 20 ppm at the wavelength of 1522.448 nm. Moreover, the detection limit is estimated to be 3.2 ppb for a lock-in integration time of 30 s.