Gas Sensing Based On Fiber Laser And Gas Absorption Spectrum

Gas sensing including gas detection and concentration measurement plays an important role in both traditional and new industry. Optical method based on gas absorption spectroscopy is widely used due to its non-contact measurement, wide measuring range and etc.. However, all the gas absorption based method has the shortcoming of small absorption signal, bad signal to noise ratio and calibration between spectra of light source and absoiption peak, so does the technique developed by this principle. So that those techniques are hard to realize low cost, miniaturization or portability, which is required by modern sensing. This article tried to find out the solution by combining the sophisticated fiber laser used in optical communication and gas absorption spectroscopy.First, an ideal light source for gas sensing is discussed. And then a fiber laser using a gas interference filter is first developed. The fiber laser is constructed of an asymmetric interferometer with a gas cell in on arm. In this way, it realized the match of wavelength between output and gas absorption peak automatically. Meanwhile, the profiles of their spectra were also in accordance. It make the light source has a bigger absoiption ration and absorption consistency under a certain wavelength drift.Moreover, a way to convert gas concentration to output wavelength drift of a fiber laser is first developed. In this way, a more precise, simpler and cheaper way to measure gas concentration is developed.