摘要
与布里渊散射不同,石英光纤中斯托克斯拉曼散射与光纤所受应力无关,只是绝对温度的函数,而且其拉曼频移为1.395×1013Hz,比布里渊散射易于提取,作为分布式光纤温度传感器的传感信号有一定的优势,但斯托克斯拉曼散射信号比布里渊弱,其峰值功率在APD中产生的光电流在nA级,低于APD的噪声电流,经光电转换后信号的信噪比小于1,傅里叶变换以及小波变换都无法有效地处理这类信号。通过对斯托克斯拉曼散射信号进行特征分析后,采用累加与小波降噪的综合方法提取该信号,实现在APD噪声电流以下的超灵敏度探测,达到每度0.104nA的温度灵敏度,低于本系统所有APD噪声电流2.3nA的1个数量级。
Unlike the Brillouin scattering, the anti-Stokes Raman scattering in optic fiber is unrelated with the strain, but is only the function of the absolute temperature. The frequency shift caused by Rarnan scattering is about 13.95 Thz. So the Raman scattering is easier to be picked up than Brillouin scattering. It has certain advantage while being used as the signal of the distributed optic-fiber temperature sensor. But it is weaker than the Brillouin scattering, the peak photocurrent produced in APD is of the order of nA, near or even lower than the noise current of the APD. The N/S after being photo-electric transformed is usually lower than 1. The means of Fourier transform and wavelet transform is not effective in dealing with such kind of signal. Through analyzing the feature of the anti-Stokes Raman scattering signal and using the wavelet, the anti-Stokes Raman scattering signal after being cumulated ＆ averaged was picked up. The supersensitive detecting below the ＂noise current＂ of the APD was carried out with the senstivity： 0. 104 nA · K^-1 ,lower than the ＂noise current＂ of the APD 2 classes.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2009年第5期1300-1303,共4页
Spectroscopy and Spectral Analysis
基金
科技部国际合作项目(2006DFB72510)
山西省国际合作项目(2006081015)
太原市科技兴市专项项目(07010709)资助
关键词
拉曼散射
光纤
噪声电流
小波变换
Raman scattering
Optic-fiber
Noise current
Wavelet
