相敏式激光啁啾色散光谱技术在高吸收度情况下的应用
发布时间：2018-08-16 16:45
【摘要】：研究了相敏式激光啁啾色散光谱法在高吸收度情况下的应用.用窄频半导体激光器作为光源,利用一工作于载波抑制模式的铌酸锂电光强度调制器调制单频激光,在单频激光两侧产生两个边频分量,并通过两边频分量产生外差干涉信号.利用外差干涉的相位波动来测量甲烷气体位于1653.7 nm附近的折射率波动,通过气体折射率与吸收系数之间的Kramers-Kronig关系计算甲烷气体浓度.传统的波长调制光谱法受限于郎伯-比尔定律,在应用于高吸收度的情况时,存在灵敏度下降的问题,甚至出现随气体浓度上升输出信号反而下降的现象.实验结果显示,相同实验条件下,波长调制光谱法的线性测量范围为38.1—1500 ppm·m,线性测量的动态范围仅为16 d B;而相敏式激光啁啾色散光谱法在很大的吸收度范围内均具有线性输出,检出限低至47.3 ppm·m,线性测量范围上限为174825 ppm·m,具有超过35 d B的动态范围.
[Abstract]:The application of phase sensitive laser chirped dispersion spectroscopy to high absorption is studied. The narrow frequency semiconductor laser is used as the light source. A single frequency laser is modulated by a lithium niobate electro-optic intensity modulator working in the carrier suppression mode. Two side frequency components are generated on both sides of the single frequency laser and heterodyne interference signals are generated by the two side frequency components. The phase fluctuation of heterodyne interference is used to measure the refractive index fluctuation of methane gas near 1653.7 nm. The concentration of methane gas is calculated by the Kramers-Kronig relation between the refractive index and absorption coefficient of methane. The traditional wavelength modulation spectral method is limited by Lombo-Beer 's law. In the case of high absorbance, the sensitivity decreases, and even the output signal decreases with the increase of gas concentration. The experimental results show that, under the same experimental conditions, The linear measurement range of wavelength modulation spectroscopy is 38.1-1500 ppm / m, and the dynamic range of linear measurement is only 16 dB, while the phase sensitive laser chirped dispersion spectroscopy has linear output in a wide range of absorption. The detection limit is as low as 47.3 ppm m, and the upper limit of linear measurement is 174825 ppm m, with a dynamic range of more than 35 dB.
【作者单位】： 清华大学精密仪器系精密测试技术及仪器国家重点实验室;
【基金】：国家重大科学仪器设备开发专项(批准号:2012YQ200182,2012YQ0901670602)资助的课题~~
【分类号】：O433
，
本文编号：2186576
[Abstract]:The application of phase sensitive laser chirped dispersion spectroscopy to high absorption is studied. The narrow frequency semiconductor laser is used as the light source. A single frequency laser is modulated by a lithium niobate electro-optic intensity modulator working in the carrier suppression mode. Two side frequency components are generated on both sides of the single frequency laser and heterodyne interference signals are generated by the two side frequency components. The phase fluctuation of heterodyne interference is used to measure the refractive index fluctuation of methane gas near 1653.7 nm. The concentration of methane gas is calculated by the Kramers-Kronig relation between the refractive index and absorption coefficient of methane. The traditional wavelength modulation spectral method is limited by Lombo-Beer 's law. In the case of high absorbance, the sensitivity decreases, and even the output signal decreases with the increase of gas concentration. The experimental results show that, under the same experimental conditions, The linear measurement range of wavelength modulation spectroscopy is 38.1-1500 ppm / m, and the dynamic range of linear measurement is only 16 dB, while the phase sensitive laser chirped dispersion spectroscopy has linear output in a wide range of absorption. The detection limit is as low as 47.3 ppm m, and the upper limit of linear measurement is 174825 ppm m, with a dynamic range of more than 35 dB.
【作者单位】： 清华大学精密仪器系精密测试技术及仪器国家重点实验室;
【基金】：国家重大科学仪器设备开发专项(批准号:2012YQ200182,2012YQ0901670602)资助的课题~~
【分类号】：O433
，
本文编号：2186576
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