利用量子级联激光器(QCL)结合新型小型化光学多通吸收池高灵敏度同时测量CO 和N2O 痕量气体。所用激光为工作在4.3 mm 附近的宽调谐、无跳模外腔量子级联激光器，激光在较短的时间内（1 s）连续波长扫描，并覆盖N2O（2203.73333 cm-1）和CO（2203.161 cm-1）两种分子的吸收谱线，从而实现对N2O 和CO 的同时测量。利用物理基长为12 cm 的新型小型化光学多通吸收池，探测光在吸收池内来回反射243次，有效光程达到29 m。利用波长调制吸收光谱和二次谐波探测技术实现了对N2O 和CO 的高灵敏度探测，测量系统的最低可探测浓度极限约为2.0×10-9（N2O）和1.7×10-9（CO）。

A quantum cascade laser (QCL)-based absorption sensor using a novel compact multi-pass gas cell (MGC) for the simultaneous monitoring of CO and N2O is reported. A wide-tunable continuous wave, mode-hopfree external-cavity QCL operating at 4.3 mm is used in the sensor. The QCL can scan over the absorption peaks of N2O (2203.73333 cm-1) and CO (2203.161 cm-1) within a short scan process (1 s), and achieve the simultaneous detection of N2O and CO. The laser is reflected for 243 times, and the cell has an effective optical path length of 29 m with the physical length of 12 cm. Wavelength modulation spectroscopy with second harmonic (2f) detection is performed to achieve the high sensitivity detection of N2O and CO. The detection limit of this sensor is 2.0 × 10-9 for N2O and 1.7×10-9 for CO.