摘要
在直接红外吸收式光纤气体传感器中,由渐变折射率(Graduated Refractive Index,GRIN)棒透镜构成的微型传感气室有着广泛的应用。分析了GRIN气室中的干涉噪声信号和甲烷信号,并利用MATLAB对干涉噪声信号的幅值与分布反馈式半导体激光器(DFBLD)的频率调制幅度之间的关系以及干涉噪声对气体检测灵敏度的影响进行了数值模拟与分析。当前谐波检测技术是气体检测的一种非常重要的技术,这种技术需要检测气体吸收信号的一次、二次或更高次谐波。而GRIN气室的二次干涉噪声对浓度信号有很大的影响,研究发现当频率调制幅度达到某些特定频率值时,二次干涉噪声信号的幅值变为零,通过调整气室参数和DFBLD的调制频率可以削减干涉噪声的影响从而提高谐波检测技术的检测灵敏度。
The micro-sensing cells composed of the GRIN lenses are widely used in the direct absorption optical fiber gas sensor. The interference noise signal and the methane signal are analyzed by MATLAB. It is simulated and analyzed by using the relationship between the noise amplitude and the amplitude of frequency modulation for DFBLD and the influence of the noise on the limit of detection. Currently, harmonic detection technology is very important in the gas detection, but it is necessary to detect the first, the second or higher harmonic. However, there is very strong second harmonic noise in the GRLN cell. Research shows that there is some amplitude of frequency modulation where the second noise is zero. The interference noise can be reduced by modifying the cell parameter and the modulation frequency, and then the detection resolution of the harmonic detection can be improved.
出处
《光学与光电技术》
2007年第6期66-68,71,共4页
Optics & Optoelectronic Technology
关键词
渐变折射率
干涉噪声
谐波检测
数值模拟
GRIN
interference noise
harmonic detection
numerical simulation
