基于非线性光学效应,采用差频发生技术(Difference frequency generation)和准相位匹配技术(Quasi-phase matching),在周期性极化的铌酸锂晶体(PPLN)中产生了中红外的可调谐激光源。泵浦光是一个功率为1W、调谐范围在770到870nm之间的...基于非线性光学效应,采用差频发生技术(Difference frequency generation)和准相位匹配技术(Quasi-phase matching),在周期性极化的铌酸锂晶体(PPLN)中产生了中红外的可调谐激光源。泵浦光是一个功率为1W、调谐范围在770到870nm之间的连续可调谐钛宝石激光器。信号光是一个功率为1W、单频连续的Nd∶YAG激光器。当晶体的光栅周期为20μm、温度调谐范围内在室温到200℃之间时,能够产生2.8μm附近的、功率约为1～2μW的差频光源。基于这个光源,采用直接吸收光谱方法测量了实验室大气中的水汽(001←000)吸收带的吸收光谱。依据大气中水汽分子在8.5cm的吸收光程条件下的吸收光谱,成功地测量得到了大气中的水汽浓度。展开更多
稳定同位素比值的测量在地质学、气象学和地球科学的研究中具有重要的应用价值。水汽同位素丰度的测量对理解与干旱相关的同温层大气科学具有重要的意义。水汽分子在2.7μm附近具有较强的吸收,适宜于高灵敏度光谱的测量。文章报道了利...稳定同位素比值的测量在地质学、气象学和地球科学的研究中具有重要的应用价值。水汽同位素丰度的测量对理解与干旱相关的同温层大气科学具有重要的意义。水汽分子在2.7μm附近具有较强的吸收,适宜于高灵敏度光谱的测量。文章报道了利用差频技术（Difference frequency generation）和准相位匹配技术（Quasi-phase matching）,将调谐范围在750~840nm之间的连续可调谐钛宝石激光器和单频连续的Nd∶YAG激光器,耦合到周期性极化铌酸锂非线性光学晶体中,产生2.5~4μm波段的中红外可调谐激光。选择周期为20μm的PPLN晶体,产生2.7μm附近的中红外差频激光,利用差频产生的中红外激光光源,具有窄线宽、宽调谐等优点。结合光程为100m的Herriott型多通吸收池,采用直接吸收光谱方法测量了实验室大气中的水汽分子同位素,得到了同位素比值R及17O,18O,D的丰度值δ,实验所测R值与国际标准具有很好的一致性。展开更多
用可调谐激光做光源,利用公里级的长程吸收光谱测量实验系统,测量高分辨率吸收光谱,拟合分析得到吸收分子的谱线参数;利用程差法测量选定波长的绝对吸收系数.通过联合分析,得到连续吸收参数.测量了实际大气和二氧化碳在1.315μm附近的...用可调谐激光做光源,利用公里级的长程吸收光谱测量实验系统,测量高分辨率吸收光谱,拟合分析得到吸收分子的谱线参数;利用程差法测量选定波长的绝对吸收系数.通过联合分析,得到连续吸收参数.测量了实际大气和二氧化碳在1.315μm附近的吸收光谱,得到氧碘激光频率(7603.1385 cm-1)的吸收截面分别为3.3x10-24和0.2 x 10-24cm2.展开更多
Direct absorption spectra of the 2v3 band of methane （CH4） from 6038 to 6050 cm 1 were studied at different low temperatures using a newly developed cryogenic cell in combination with a distributed feedback （DFB） ...Direct absorption spectra of the 2v3 band of methane （CH4） from 6038 to 6050 cm 1 were studied at different low temperatures using a newly developed cryogenic cell in combination with a distributed feedback （DFB） diode laser. The cryogenic cell can operate at any stabilized temperature ranging from room temperature down to 100 K with temperature fluctuation less than =t=1 K within 1 hour. In the present work, the CH4 spectra in the range of 6038-6050 cm-1 were recorded at 296, 266, 248, 223, 198, and 176 K. The lower state energy Ett and the rotational assignment of the angular momentum J were determined by a ＂2-low-temperature spectra method＂ using the spectra recorded at 198 and 176 K. The results were compared with the data from the GOSAT and the recently reported results from Campargue and co-workers using two spectra measured at room temperature and 81 K. We demonstrated that the use of a 2-low-temperature spectra method permits one to complete the Ett and J values missed in the previous studies.展开更多
文摘基于非线性光学效应,采用差频发生技术(Difference frequency generation)和准相位匹配技术(Quasi-phase matching),在周期性极化的铌酸锂晶体(PPLN)中产生了中红外的可调谐激光源。泵浦光是一个功率为1W、调谐范围在770到870nm之间的连续可调谐钛宝石激光器。信号光是一个功率为1W、单频连续的Nd∶YAG激光器。当晶体的光栅周期为20μm、温度调谐范围内在室温到200℃之间时,能够产生2.8μm附近的、功率约为1～2μW的差频光源。基于这个光源,采用直接吸收光谱方法测量了实验室大气中的水汽(001←000)吸收带的吸收光谱。依据大气中水汽分子在8.5cm的吸收光程条件下的吸收光谱,成功地测量得到了大气中的水汽浓度。
文摘稳定同位素比值的测量在地质学、气象学和地球科学的研究中具有重要的应用价值。水汽同位素丰度的测量对理解与干旱相关的同温层大气科学具有重要的意义。水汽分子在2.7μm附近具有较强的吸收,适宜于高灵敏度光谱的测量。文章报道了利用差频技术（Difference frequency generation）和准相位匹配技术（Quasi-phase matching）,将调谐范围在750~840nm之间的连续可调谐钛宝石激光器和单频连续的Nd∶YAG激光器,耦合到周期性极化铌酸锂非线性光学晶体中,产生2.5~4μm波段的中红外可调谐激光。选择周期为20μm的PPLN晶体,产生2.7μm附近的中红外差频激光,利用差频产生的中红外激光光源,具有窄线宽、宽调谐等优点。结合光程为100m的Herriott型多通吸收池,采用直接吸收光谱方法测量了实验室大气中的水汽分子同位素,得到了同位素比值R及17O,18O,D的丰度值δ,实验所测R值与国际标准具有很好的一致性。
文摘用可调谐激光做光源,利用公里级的长程吸收光谱测量实验系统,测量高分辨率吸收光谱,拟合分析得到吸收分子的谱线参数;利用程差法测量选定波长的绝对吸收系数.通过联合分析,得到连续吸收参数.测量了实际大气和二氧化碳在1.315μm附近的吸收光谱,得到氧碘激光频率(7603.1385 cm-1)的吸收截面分别为3.3x10-24和0.2 x 10-24cm2.
基金Project supported by the National Natural Science Foundation of China(Grant No.41175036)
文摘Direct absorption spectra of the 2v3 band of methane （CH4） from 6038 to 6050 cm 1 were studied at different low temperatures using a newly developed cryogenic cell in combination with a distributed feedback （DFB） diode laser. The cryogenic cell can operate at any stabilized temperature ranging from room temperature down to 100 K with temperature fluctuation less than =t=1 K within 1 hour. In the present work, the CH4 spectra in the range of 6038-6050 cm-1 were recorded at 296, 266, 248, 223, 198, and 176 K. The lower state energy Ett and the rotational assignment of the angular momentum J were determined by a ＂2-low-temperature spectra method＂ using the spectra recorded at 198 and 176 K. The results were compared with the data from the GOSAT and the recently reported results from Campargue and co-workers using two spectra measured at room temperature and 81 K. We demonstrated that the use of a 2-low-temperature spectra method permits one to complete the Ett and J values missed in the previous studies.
