Experimental demonstration of a fiber-optic gas sensor network addressed by FMCW

We report on the use of frequency-modulated continuous-wave and wavelength modulation spectroscopy techniques for addressing a multipoint gas sensor network. A three-sensor network of ladder topology is experimentally demonstrated for the detection of acetylene gas. A minimum detectable concentration of 270 ppm//spl radic/Hz is obtained with 25-mm gas cells under atmospheric pressure which corresponds to a minimum detectable absorbance of 3.40/spl times/10/sup -4/. The crosstalk between the sensors is below -22 dB.