A sensor using a single distributed-feedback (DFB) diode laser at 1.57 μm for the simultaneous measurement of CO<sub>2</sub> and CO concentration at elevated temperatures is developed. A proper line pair near 6361.250 and 6361.344 cm<sup>–1</sup> is chosen based on absorption strength, separation of the two lines, and isolation from interference of neighboring transitions of the major combustion gases. The concentrations of CO<sub>2</sub> and CO are inferred from their wavelength modulation spectroscopy (WMS) 1ƒ-normalized absorption-based WMS-2ƒ signal peak heights. The CO<sub>2</sub> and CO concentration measurements are within 3.3% and 5% of the expected values over the full temperature range.
Tingdong Cai, Guangzhen Gao, Weidong Chen, Gang Liu, and Xiaoming Gao, "Simultaneous Measurements of CO2 and CO Using a Single Distributed-Feedback (DFB) Diode Laser Near 1.57 μm at Elevated Temperatures," Appl. Spectrosc. 65, 108-112 (2011)