Here we present a high-sensitivity, rapid, and low-cost method for methane sensing based on a nonlinear interferometer. This method utilizes signal photons generated by stimulated parametric down-conversion (ST-PDC), enabling the use of a silicon detector to capture high-precision methane absorption spectra in the mid-infrared region. By controlling the system loss, we achieve more significant changes in visibility, thereby increasing sensitivity. The methane concentration within a gas cell is determined accurately. In addition, ST-PDC enables long-distance sensing and the capability to measure low ambient methane concentrations in the real world. A low-cost CMOS camera is employed to capture spatial interference fringes, ensuring fast and efficient detection.
@article{arxiv.2407.20201,
title = {Methane Sensing via Unbalanced Nonlinear Interferometry using a CMOS Camera},
author = {Jinghan Dong and Arthur C. Cardoso and Haichen Zhou and Jingrui Zhang and Weijie Nie and Alex S. Clark and John G. Rarity},
journal= {arXiv preprint arXiv:2407.20201},
year = {2024}
}