【摘要】：研究了相敏式激光啁啾色散光譜法在高吸收度情況下的應用.用窄頻半導體激光器作為光源,利用一工作于載波抑制模式的鈮酸鋰電光強度調(diào)制器調(diào)制單頻激光,在單頻激光兩側(cè)產(chǎn)生兩個邊頻分量,并通過兩邊頻分量產(chǎn)生外差干涉信號.利用外差干涉的相位波動來測量甲烷氣體位于1653.7 nm附近的折射率波動,通過氣體折射率與吸收系數(shù)之間的Kramers-Kronig關系計算甲烷氣體濃度.傳統(tǒng)的波長調(diào)制光譜法受限于郎伯-比爾定律,在應用于高吸收度的情況時,存在靈敏度下降的問題,甚至出現(xiàn)隨氣體濃度上升輸出信號反而下降的現(xiàn)象.實驗結(jié)果顯示,相同實驗條件下,波長調(diào)制光譜法的線性測量范圍為38.1—1500 ppm·m,線性測量的動態(tài)范圍僅為16 d B;而相敏式激光啁啾色散光譜法在很大的吸收度范圍內(nèi)均具有線性輸出,檢出限低至47.3 ppm·m,線性測量范圍上限為174825 ppm·m,具有超過35 d B的動態(tài)范圍.
[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.
【作者單位】： 清華大學精密儀器系精密測試技術及儀器國家重點實驗室;
【基金】：國家重大科學儀器設備開發(fā)專項(批準號:2012YQ200182,2012YQ0901670602)資助的課題~~
【分類號】：O433
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本文編號：2186576