title: Miniature fiber-tip photoacoustic spectrometer for trace gas detection.
abstract: We demonstrate a fiber-tip photoacoustic spectrometric sensor for trace gas detection. The sensor head is a miniature fiber-tip hollow-cavity with a deflectable polymer diaphragm. Periodic light absorption of gas molecules within the cavity generates an acoustic pressure wave, which causes deflection of the diaphragm. The hollow cavity also is a Fabry-Perot interferometer with which the diaphragm deflection is detected with high sensitivity. Experimental test around the P(9) absorption line of C(2)H(2) achieved a minimum detectable gas concentration of 4.3 ppm with an excitation laser power of 8 mW. The miniature sensor head and fiber optic detection system make this type of spectrometers ideally suited for remote and space-limited applications as well as for multipoint detection in a multiplexed fiber optic sensor network.
authors: Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
authors: Yingchun
authors: Y
authors: Cao
authors: Wei
authors: W
authors: Jin
authors: Hoi Lut
authors: HL
authors: Ho
authors: Jun
authors: J
authors: Ma