Abstract: A gas sensor using optical spectrometry and dedicated to a specific gas is studied. It should be able to operate out of laboratories with a very long life and a low maintenance requirement. It is based on TLDS (tunable laser diode spectroscopy) and uses a standard Perot-Fabry laser diode already developed for telecommunications. The mode selection is realized by a passband filter and the wavelength tuning is performed via the diode temperature or its injection current. A PIN photodiode is used for detection, however a rough photoacoustic solution is intended for the future. Absorptions as low as 3.10$+$MIN@3$/ are detected with this rough system and a limit detection of 10$+$MIN@3$/ is available with a signal to noise ratio of unity. Experiments have shown that this system is strongly selective for the specified gas (currently the methane). A simulation has been performed which very well fits the experiment and allows us to extrapolate the performances of the system for other gases. !6
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