High-sensitivity off-axis integrated cavity output spectroscopy implementing wavelength modulation and white noise perturbation

In this Letter, a new method is proposed to further improve the detection sensitivity of the gas sensor based on off-axis integrated cavity spectroscopy (OA-ICOS) using a distributed feedback laser operating in the near-infrared at 1653 nm that relies on implementation of wavelength modulation and radio frequency (RF) white noise perturbation to diode laser current. More than sixfold improvement in detection limit is achieved for an RF noised wavelength-modulated OA-ICOS compared to the unperturbed conventional OA-ICOS approach.