Abstract
The key techniques for the high-sensitivity detection of CO2 in the 2 μm band are studied based on photo-thermal spectroscopy in a hollow-core optical fiber, and a low-sharpness Fabry-Perot interferometer based on anti-resonance hollow-core optical fiber is adopted to demodulate the photo-thermal phase. For the R(18) absorption line of CO2 at 2004.02 nm, the noise equivalent volume fraction is about 4.7×10 -8 with a pump power of 180 mW and integration time of 1 s. To improve the stability of the detection system, we suppress the intra-cavity interference of pump light by applying the anti-reflection coating to the fiber end face and lock the probe wavelength to the quadrature point of the interferometer. Within 1 h, the signal fluctuation corresponding to CO2 standard gas with volume fraction of 10 -5 is about 4.7%. Noise analysis shows that the noise mainly comes from the phase noise and intensity noise of the probe laser in the current detection system.
| Original language | English |
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| Article number | 136004 |
| Journal | Guangxue Xuebao/Acta Optica Sinica |
| Volume | 41 |
| Issue number | 13 |
| Publication status | Published - Jul 2021 |