Related Experiment Video
Updated: Apr 3, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Dual wavelength 3.2-μm source for isotope ratio measurements of (13)CH(4)/(12)CH(4)
Abstract:
Difference frequency generation using one 1.58-μm and two 1.06-μm distributed feedback Bragg-grating laser diodes and a ridge-type PPLN alternately provide two 3.2-μm coaxial waves resonant with individual isotopic transitions separated by 13 cm(-1). The ν(3) band R(6) A(2) allowed transition of (13)CH(4) and the ν(3) band R(6) A(2) weakly allowed transition of (12)CH(4) are an ideal pair for isotope ratio measurements. The (13)CH(4)/(12)CH(4) isotope ratio is determined for three sample gases with a relative uncertainty of 0.7 ‰, and it is confirmed that the temperature dependence is smaller than the uncertainty.
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