中文摘要：

可调谐二极管激光吸收光谱技术中的波长调制方法具有适应恶劣环境以及灵敏度高等特点,在气体浓度测量方面得到了广泛应用。与常用的正弦波调制相比,三角波调制方式具有更高的灵敏度,但一般采用标定的方法来实现气体浓度的测量。提出了基于三角波调制的免标定波长调制方法,建立了分布反馈激光器在三角波调制下的频率响应模型。实验结果表明,使用所提频率响应关系式可使标准具信号拟合结果的相对残差小于0.4%,一次谐波归一化二次谐波信号拟合结果的相对残差小于1.2%,证明了该模型的可行性;实现了基于三角波调制的CH4气体浓度的免标定测量。

英文摘要：

The wavelength modulation method in tunable diode laser absorption spectroscopy is widely used in the measurement of gas concentration due to its advantages of adapting to harsh environment and high sensitivity. Compared with the common sine wave modulation, the triangular modulation has higher sensitivity. However, the triangular modulation method is generally combined with the calibration approach to measure gas concentration. In this study, a new calibration-free method based on triangular wave modulation is proposed and a frequency response model of distributed feedback laser is developed. The experimental results illustrate that the relative residual of etalon signal is less than 0.4% and the relative residual of the first harmonic normalized second harmonic signal is less than 1.2%, which prove the feasibility of the proposed model. The calibration-free measurement of CH4 gas concentration based on triangular wave modulation is realized.