SG-DBR半导体激光器的光谱技术研究

可调谐半导体激光吸收光谱作为一种高灵敏度、高选择性、非侵入的痕量气体实时检测技术，已在大气监测、工业控制等方面得到广泛应用。采用一种新型宽带可调谐的SG-DBR半导体激光器(可调谐范围1 520~1 570 nm)作光源，并通过自编程序对该激光器设定了18个通道，输出波长分别对应CO，CO₂以及H₂O的吸收谱线中心位置，设计和构建了一个基于近红外可调谐半导体激光吸收光谱的多组分气体光谱测量系统，描述了相关的光学系统设置，结合波长调制(wm)的二次谐波技术测量其中14个通道(分别对应CO和CO₂的吸收谱线)的吸收光谱，系统获得的CO和CO₂峰值吸收探测极限能够达到10-5。实验结果验证了SG-DBR激光器在波长调制吸收光谱多组分气体检测领域的可行性。在实际应用过程中使用单个SG-DBR激光器可以实现多组分气体的同时测量，有效降低设备成本和系统复杂性。

Research on Spectrum Technology Based on SG-DBR Laser

Tunable diode laser absorption spectroscopy (TDLAS) is a highly sensitive, highly selective, noninvasive and real-time trace gas detection technique, which has been widely used in atmospheric monitoring and industrial control. In the present research, a new type of widely tunable SG-DBR diode laser (WTDL) with a tunable range of about 1 520~1 570 nm was use as the light source for tunable diode laser absorption spectroscopy combined with the wavelength modulation (wm) to measure the spectrum of multi-gases. Also the structure, performance and other characteristics of WTDL were introduced. There were 18 channels compiled to the SG-DBR laser, which emitted central wavelength at the optimum absorption transitions of CO, CO₂ and H₂O by homemade program, of which 14 channels (corresponding to absorption lines of CO and CO₂) were investigated by second harmonic detection technique. Meanwhile, the detectabilities in these channel were analyzed which are about 10-5 at the peak absorbance. The experiment results validate the feasibility of SG-DBR laser used as light source in multi-gases detection using wavelength modulation absorption spectroscopy technique in practical application. That could effectively reduce the cost and complexity of system in the field of TDLAS technique.