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Updated: Jun 13, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Ultrasensitive near-infrared cavity ring-down spectrometer for precise line profile measurement
Bo Gao1, Wei Jiang, An-Wen Liu
1Department of Chemical Physics, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
Abstract:
A cavity ring-down (CRD) spectrometer is built with a continuous-wave Ti:sapphire ring laser. Using a pair of R approximately 0.999 95 high-reflective mirrors, the noise-equivalent minimum detectable absorption loss reaches 7 x 10(-11)/cm over the spectral range of 780-830 nm. A thermal-stabilized Fabry-Perot interferometer is applied to calibrate the CRD spectrum with an accuracy of 1 x 10(-4) cm(-1). The quantitative measurement is carried out for the line profile measurements of some overtone absorption lines of C(2)H(2) near 787 nm. Doppler determined line shape has been observed with milli-Torr acetylene gas in the ring-down cavity. The instrumental line width is estimated from the line profile fitting to be <1 x 10(-4) cm(-1). It demonstrates that the CRD spectrometer with extremely high sensitivity is also very suitable for quantitative measurements including precise line profile studies in the near-infrared.
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