Sensitive carbon monoxide detection based on light-induced thermoelastic spectroscopy with a fiber-coupled multipass cell [Invited]

A sensor based on light-induced thermoelastic spectroscopy (LITES) with a fiber-coupled multipass cell was demonstrated for carbon monoxide (CO) detection. The fiber-coupled structure has the merits of reducing optical interference and difficulty in optical alignment and increasing system robustness. A 1.57 μm continuous wave distributed feedback diode laser was used as the excitation source. A minimum detection limit of 9 ppm was obtained, and the calculated normalized noise equivalent absorption coefficient was 1.15 × 10⁻⁷ cm⁻¹ · W · Hz⁻¹=². The reported CO-LITES sensor showed excellent linear concentration response and system stability.