使用准连续二极管激光器进行多重调制光谱检测时， 发现吸收光谱信号中存在着丰富的倍频、 和频以及差频成分； 从激光与气体吸收谱线的非线性作用角度研究了倍频、 和频及差频等信号存在的必然性； 从实验角度对信号特征进行研究， 发现其中有些和频、 差频成分的幅度比传统调谐二极管激光吸收光谱技术中的二次谐波信号的幅度更大， 有望在准连续调制谱技术中提高检测的灵敏度。

Numerous harmonic components such as multiple frequency, sum frequency and difference frequency of multiple modulation signals were found in quasi-continuous-wave (QCW) diode laser modulation absorption spectroscopy. Then, the authors analyzed these harmonic components’ existence in terms of non-linear interactions of laser and gas absorption line. And the signals’ characteristics were studied experimentally. The results shows that there are some sum frequency and difference frequency components that have larger amplitudes compared to the second harmonic wavelength modulation spectroscopy signal (2f-WMS) commonly used in tunable diode laser spectroscopy (TDLAS), and it may improve the detection sensitivity of QCW modulation spectroscopy.