基于单个量子级联激光器的大气多组分测量方法
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摘要
利用单个新型中红外量子级联激光器作为激光光源,结合长程光学吸收池技术开展了大气多组分同时测量方法的研究.通过结合基于自适应性Savitzky-Golay滤波的数据处理算法,有效地提高了系统检测灵敏度和光谱分辨率.研究结果表明,在1 s的时间分辨率和1 atm压力条件下,采用二次微分探测技术可实现CO,N_2O和H_2O测量精度分别为8.20 ppb,7.90 ppb和64.00 ppm(1 ppb=10~(-9),1 ppm=10~(-6));通过提高信号平均时间,在最佳的积分时间(85 s)时,系统可实现的最小检测限分别为1.25 ppb(CO),1.15 ppb(N_2O)和35.77 ppm(H_2O).整个系统具有结构紧凑,成本相对较低,通过选择其他波段的量子级联激光器的激光光源,即可实现对其他分子的实时分析.本系统可广泛应用于大气化学等领域的应用研究.
Quantum cascade lasers(QCLs) are relatively new sources of mid-infrared radiation(between 2.5 μm and 25 μm),and are very well suited to the application of in-field trace gas sensing,mainly due to their superiority of being robust,compact,wavelength-versatile,narrow line width and low power consumption.All these advantages make the laser absorption spectroscopy based on QCL light sources become one of the most popular technologies for the quantitative chemical detection in a variety of fields including atmospheric environmental monitoring,chemical analysis,industrial process control,medical diagnostics,security or bio-medical studies,etc.In the present work,a highly sensitive mid-infrared gas sensor employing a single continuous-wave distributed feedback QCL and an astigmatic multi-path optical absorption cell is demonstrated for the simultaneous measurement of atmospheric carbon monoxide(CO),nitrous oxide(N_2O) and water vapor(H_2O).By combining with an adaptive Savitzky-Golay(S-G) filter signal processing algorithm,the detection sensitivity and spectral resolution of the QCL sensor system are significantly improved.Compared with the traditional wavelet transform based signal de-noising technique,the developed adaptive S-G smoothing filter shows obvious advantages in terms of computational efficiency and selection of the optimal filter parameters,namely only two filter parameters(the width of the smoothing window and the degree of the smoothing polynomial) need to be considered.Currently,the QCL sensor system is estimated for the long term measurement of ambient air in laboratory environment.The results show that measurement precisions of8.20 ppb(1 ppb = 10-9) for CO,7.90 ppb for N_2O,and 64.00 ppm(1 ppm = 10~(-6)) for H_2O at 1 s time resolution and1 atmospheric pressure(atm) are obtained by using the quadratic differential detection scheme,which can be further improved to 1.25 ppb(for CO),1.15 ppb(for N_2O) and 35.77 ppm(for H_2O) by increasing average time up to 85 s,respectively.On the whole,the QCL sensor system has significant features of portability and low-cost,moreover,it can be easily modified for the real-time analysis of other gas molecules through the choosing of corresponding QCL light sources.The QCL gas sensor can be widely used in the field of atmospheric chemistry and other applications.Future work will focus on H_2O induced broadening coefficients for CO and N_2O transitions near 4.57 μm,which will be updated for the developed multi-species QCL sensor system,thus resolving the influence of water vapor broadening effect and achieving the measurement of gas concentration in a high humid environment with sub-percent precision.
Quantum cascade lasers(QCLs) are relatively new sources of mid-infrared radiation(between 2.5 μm and 25 μm),and are very well suited to the application of in-field trace gas sensing,mainly due to their superiority of being robust,compact,wavelength-versatile,narrow line width and low power consumption.All these advantages make the laser absorption spectroscopy based on QCL light sources become one of the most popular technologies for the quantitative chemical detection in a variety of fields including atmospheric environmental monitoring,chemical analysis,industrial process control,medical diagnostics,security or bio-medical studies,etc.In the present work,a highly sensitive mid-infrared gas sensor employing a single continuous-wave distributed feedback QCL and an astigmatic multi-path optical absorption cell is demonstrated for the simultaneous measurement of atmospheric carbon monoxide(CO),nitrous oxide(N_2O) and water vapor(H_2O).By combining with an adaptive Savitzky-Golay(S-G) filter signal processing algorithm,the detection sensitivity and spectral resolution of the QCL sensor system are significantly improved.Compared with the traditional wavelet transform based signal de-noising technique,the developed adaptive S-G smoothing filter shows obvious advantages in terms of computational efficiency and selection of the optimal filter parameters,namely only two filter parameters(the width of the smoothing window and the degree of the smoothing polynomial) need to be considered.Currently,the QCL sensor system is estimated for the long term measurement of ambient air in laboratory environment.The results show that measurement precisions of8.20 ppb(1 ppb = 10-9) for CO,7.90 ppb for N_2O,and 64.00 ppm(1 ppm = 10~(-6)) for H_2O at 1 s time resolution and1 atmospheric pressure(atm) are obtained by using the quadratic differential detection scheme,which can be further improved to 1.25 ppb(for CO),1.15 ppb(for N_2O) and 35.77 ppm(for H_2O) by increasing average time up to 85 s,respectively.On the whole,the QCL sensor system has significant features of portability and low-cost,moreover,it can be easily modified for the real-time analysis of other gas molecules through the choosing of corresponding QCL light sources.The QCL gas sensor can be widely used in the field of atmospheric chemistry and other applications.Future work will focus on H_2O induced broadening coefficients for CO and N_2O transitions near 4.57 μm,which will be updated for the developed multi-species QCL sensor system,thus resolving the influence of water vapor broadening effect and achieving the measurement of gas concentration in a high humid environment with sub-percent precision.
引文
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[4]Jia M Y,Zhao G,Hou J J,Tan W,Qiu X D,Ma W G,Zhang L,Dong L,Yin W B,Xiao L T,Jia S T 2016Acta Phys.Sin.65 128701(in Chinese)[贾梦源,赵刚,侯佳佳,谭巍,邱晓东,马维光,张雷,董磊,尹王保,肖连团,贾锁堂2016物理学报65 128701]
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[7]Li J S,Chen W,Fischer H 2013 Appl.Spectrosc.Rev.48 523
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[9]Tao L,Sun K,Khan M A,Miller D J,Zondlo M A 2012Opt.Express 20 28106
[10]Ren W,Jiang W Z,Tittel F K 2014 Appl.Phys.B 117245
[11]Dong L,Yu Y,Li C,So S,Tittel F K 2015 Opt.Express23 19821
[12]Dong L,Tittel F K,Li C,Sanchez P N,Wu H,Zheng C,Yu Y,Sampaolo A,Griffin R J 2016 Opt.Express 24A528
[13]Dong L,Li C,Sanchez N P,Gluszek A K,Griffin R J,Tittel F K 2016 Appl.Phys.Lett.108 011106
[14]Yu Y,Sanchez N P,Griffin R J,Tittel F K 2016 Opt.Express 24 10391
[15]Wen Z Q,Chen G,Peng C,Yuan W Q 2013 Spectrosc.Spect.Anal.33 949(in Chinese)[温中全,陈刚,彭琛,袁伟青2013光谱学与光谱分析33 949]
[16]Ma Y,He Y,Yu X,Zhang J,Sun R,Tittel F K 2016Appl.Phys.Lett.108 091115
[17]Tang Y,Liu W,Kan R,Liu J,He Y,Zhang Y,Xu Z,Ruan J,Geng H 2011 Opt.Express 19 20224
[18]Tan S,Liu W F,Wang L J,Zhang J C,Li L,Liu J Q,Liu F Q,Wang Z G 2012 Spectrosc.Spect.Anal.32 1251(in Chinese)[谭松,刘万峰,王利军,张锦川,李路,刘俊岐,刘峰奇,王占国2012光谱学与光谱分析32 1251]
[19]Savitzky A,Golay M J 1964 Anal.Chem.36 1627
[20]Rothman L S,Gordon I E,Babikov Y,Barbe A,Benner D C,Bernath P F,Birk M,Bizzocchi L,Boudon V,Brown L R,Campargue A,Chance K,Coudert L H,Devi V M,Drouin B J,Fayt A,Flaud J M,Gamache R R,Harrison J,Hartmann J M,Hill C,Hodges J T,Jacquemart D,Jolly A,Lamouroux J,Le Roy R J,Li G,Long D,Mackie C J,Massie S T,Mikhailenko S,Müller H S P,Naumenko O V,Nikitin A V,Orphal J,Perevalov V I,Perrin A,Polovtseva E R,Richard C,Smith M A H,Starikova E,Sung K,Tashkun S A,Tennyson J,Toon G C,Tyuterev V G,Wagner G 2013 J.Quant.Spectrosc.Radiat.Transfer 130 4
[21]Li J S,Deng H,Li P F,Yu B L 2015 Appl.Phys.B 120207
[22]Li J S,Parchatka U,Fischer H 2012 Appl.Phys.B 108951
[23]Werle P,Miicke R,Slemr F 1993 Appl.Phys.B 57 131
[2]Ma Y,Lewicki R,Razeghi M,Tittel F K 2013 Opt.Express 21 1008
[3]Wang F,Huang Q X,Li N,Yan J H,Chi Y,Cen K F2007 Acta Phys.Sin.56 3867(in Chinese)[王飞,黄群星,李宁,严建华,池涌,岑可法2007物理学报56 3867]
[4]Jia M Y,Zhao G,Hou J J,Tan W,Qiu X D,Ma W G,Zhang L,Dong L,Yin W B,Xiao L T,Jia S T 2016Acta Phys.Sin.65 128701(in Chinese)[贾梦源,赵刚,侯佳佳,谭巍,邱晓东,马维光,张雷,董磊,尹王保,肖连团,贾锁堂2016物理学报65 128701]
[5]Zhao Y,Zhao X H,Wang Z,Zhang R,Wang Y 2015Spectrosc.Spect.Anal.35 3224(in Chinese)[赵迎,赵学玒,王喆,张锐,汪曣2015光谱学与光谱分析35 3224]
[6]Curl R F,Capasso F,Gmachl C,Kosterev A A,McManus B,Lewicki R,Tittel F K 2010 Chem.Phys.Lett.487 1
[7]Li J S,Chen W,Fischer H 2013 Appl.Spectrosc.Rev.48 523
[8]Li J S,Parchatka U,Fischer H 2013 Sens.Actuat.B182 659
[9]Tao L,Sun K,Khan M A,Miller D J,Zondlo M A 2012Opt.Express 20 28106
[10]Ren W,Jiang W Z,Tittel F K 2014 Appl.Phys.B 117245
[11]Dong L,Yu Y,Li C,So S,Tittel F K 2015 Opt.Express23 19821
[12]Dong L,Tittel F K,Li C,Sanchez P N,Wu H,Zheng C,Yu Y,Sampaolo A,Griffin R J 2016 Opt.Express 24A528
[13]Dong L,Li C,Sanchez N P,Gluszek A K,Griffin R J,Tittel F K 2016 Appl.Phys.Lett.108 011106
[14]Yu Y,Sanchez N P,Griffin R J,Tittel F K 2016 Opt.Express 24 10391
[15]Wen Z Q,Chen G,Peng C,Yuan W Q 2013 Spectrosc.Spect.Anal.33 949(in Chinese)[温中全,陈刚,彭琛,袁伟青2013光谱学与光谱分析33 949]
[16]Ma Y,He Y,Yu X,Zhang J,Sun R,Tittel F K 2016Appl.Phys.Lett.108 091115
[17]Tang Y,Liu W,Kan R,Liu J,He Y,Zhang Y,Xu Z,Ruan J,Geng H 2011 Opt.Express 19 20224
[18]Tan S,Liu W F,Wang L J,Zhang J C,Li L,Liu J Q,Liu F Q,Wang Z G 2012 Spectrosc.Spect.Anal.32 1251(in Chinese)[谭松,刘万峰,王利军,张锦川,李路,刘俊岐,刘峰奇,王占国2012光谱学与光谱分析32 1251]
[19]Savitzky A,Golay M J 1964 Anal.Chem.36 1627
[20]Rothman L S,Gordon I E,Babikov Y,Barbe A,Benner D C,Bernath P F,Birk M,Bizzocchi L,Boudon V,Brown L R,Campargue A,Chance K,Coudert L H,Devi V M,Drouin B J,Fayt A,Flaud J M,Gamache R R,Harrison J,Hartmann J M,Hill C,Hodges J T,Jacquemart D,Jolly A,Lamouroux J,Le Roy R J,Li G,Long D,Mackie C J,Massie S T,Mikhailenko S,Müller H S P,Naumenko O V,Nikitin A V,Orphal J,Perevalov V I,Perrin A,Polovtseva E R,Richard C,Smith M A H,Starikova E,Sung K,Tashkun S A,Tennyson J,Toon G C,Tyuterev V G,Wagner G 2013 J.Quant.Spectrosc.Radiat.Transfer 130 4
[21]Li J S,Deng H,Li P F,Yu B L 2015 Appl.Phys.B 120207
[22]Li J S,Parchatka U,Fischer H 2012 Appl.Phys.B 108951
[23]Werle P,Miicke R,Slemr F 1993 Appl.Phys.B 57 131