Dynamic Linewidth Measurements And Application Research On Trace Gas Detection Of Interband Cascade Lasers

The Interband Cascade Laser(ICL)is a new kind of mid infrared laser of excellent characteristics such as narrow linewidth,low power consumption and long life.It attracts great concerns because of the great advantage in gas sensing field.And the laser linewidth is a key evaluation parameter of laser performance.For example,it determines the resolution of measured gas spectral resolution.Hence,this thesis aims at carrying out the research on the measurement of the dynamic linewidth of the ICL.And based on the analysis to the dynamic spectral properties of ICLs,we realized the optimization in the gas detection.Firstly,the design,test and demonstration of the ICL module were represented.Firstly in order to ensure the safety use of ICL,the parts of ICL standard molecule,such as the three dimensional adjustment component,insulation protection component and temperature control component were respectively designed,fabricated.And the tests on the module of functions were conducted.The experimental results show that the ICL standard moledule not only realizes the functions of the fine tuning of optical path and collimating,and effectively reduces the laser work load,improves the operation stability of the laser.Secondly,the design,test and demonstration of dynamic linewidth measurement apparatus were represented.The dynamic linewidth measurement apparatus was developed.It can be used for investigating difference of the measuring dynamic linewidth with the multiple choices of ultra short-delay time.Due to its wide universality,it also can be used for measuring the dynamic linewidth of variety of tunable lasers.For example,base on the apparatus,the dynamic linewidth and the dynamic injection current tuning rate of ICL,Quantum Cascade Laser(QCL)and Diode Laser(LD)were measured and discussed.Moreover,the relationship between the dynamic spectral properties with the laser operating current,the tuning frequency and the operating temperature were measured and discussed.Thirdly,the design of the dimethyl sulfide laser gas analyzer with a light source of ICL was represented.Firstly,the dimethyl sulfide laser gas analyzer was developed.And according to the spectral characteristics of the ICL,the modulation parameters were optimized,and the signal-to-noise ratio was greatly improved.Finally a comprehensive evaluation of the performance of the analyzer was detailed such as linear fitting correlation of 99.98%,detection limit of 40.5 ppb,uncertainty of measurement of 0.17% FS.It meets the monitoring requirement of low concentration dimethyl sulfide.In this thesis,the ICL standard module has effectively ensured the working requirements under complex conditions.It has been successfully used in the dynamic linewidth measurement apparatus,the dimethyl sulfide laser gas analyzer,etc.The measurement apparatus of laser dynamic linewidth was developed for the first time.And based on the apparatus,we realized the measurement of dynamic spectral properties of multiple DFB tunable lasers and investigated their relationships with laser operating current,tuning frequency and operating temperature.And the dynamic spectral properties of ICL are reported for the first time.The gas analyzer based on ICL for monitoring methyl sulfide was developed,which possess high sensitivity,detection specificity,fast response and long life.It can meet the basic real-time,online requirements of monitoring dimethyl sulfide in industrial waste gas.