Yeqing Liu, Kaisheng Huang

(College of Physics and Energy, Fujian Normal University)

Abstract：

A broadband tunable narrow linewidth thulium doped fiber laser amplifier was developed using the broadband emission characteristics of thulium doped fiber in the 2μm band and the linewidth compression characteristics of the fiber saturable absorber. The amplifier can amplify the power of a narrow linewidth, broadband tunable seed light source to 290mW, and the amplified light source can run continuously for 30 minutes with root mean square stability better than 1%. The wide absorption spectrum of water molecules in the 2μm band was tested using any one of the 32 laser channels output by a laser amplifier, and the test results were used to invert the linewidth of the light source during dynamic scanning, which was approximately 0.06nm. The temperature and mole fraction of water molecules in air and alcohol flames were tested using the laser amplifier. The results showed that at room temperature, the average temperatures in air and alcohol flames were 301.2,1263.3K, with relative deviations of 1.28%, 3.08%, the average molar fractions of water molecules are 2.11%, 5.58%. The use of this light source can effectively obtain wideband laser absorption spectra of water molecules in the 2μm wavelength range. These absorption spectrum data can accurately reflect environmental temperature, water molecule mole fraction, and other information. The results verify the feasibility of this laser light source in the application of 2D tomographic diagnostic measurement of combustion flow fields.

Key Words：

absorption spectroscopy; tunable diode laser absorption spectroscopy technology; wide band absorption spectroscopy technology; combustion flow field; thulium doped fiber laser amplifier