All-fiber pressure-adaptive CO2 concentration monitoring based on negative curvature anti-resonance hollow core fiber

Greenhouse gas detection is a key foundation for combating climate change and provides indispensable data support for scientific assessment of carbon emissions and their environmental impacts. In this study, an all-fiber pressure-adaptive gas concentration monitoring system based on tunable diode laser absorption spectroscopy-wavelength modulation spectroscopy is presented. Within a negative curvature-anti-resonant hollow-core optical fiber, the system achieves simultaneous gas concentration detection and ambient pressure monitoring. A pressure compensation algorithm is implemented to dynamically compensate measured gas concentrations to standardized values at the target pressure under fluctuating ambient pressures. The method effectively suppresses concentration measurement instability induced by pressure fluctuations. Experimental results demonstrate a significant improvement: under 20 kPa pressure variations, the 1-h relative standard deviation of CO₂ concentration measurement is reduced from 3.60 % to 1.36 %. Simultaneously, the minimum detection limit is optimized from 121.4 ppm to 34.3 ppm at a 10-s integration time.