Numerical Optimization And Photoelectric Modulation Characteristics Of Quantum Cascade Laser

It is well known that Einstein's theory of stimulated radiation laid the theoretical foundation for the production of lasers.According to the working medium,lasers can be divided into gas lasers,solid-state lasers,semiconductor lasers and dye lasers.Quantum cascade laser is a semiconductor laser,which is a high-performance coherent light source.It has the advantages of high power,narrow linewidth,and tunable output wavelength.Its output wavelength has been increased from the mid-infrared band to the terahertz band.It has broad application prospects in the fields of molecular spectroscopy,gas detection,medical diagnosis,chemical sensing,free space optical communication,industrial production process control and so on.In this paper,the output characteristics of quantum cascade lasers are studied comprehensively and deeply from both theoretical and experimental aspects.Theoretically,with the help of MATLAB analysis software,using the transfer matrix method and the finite difference method to solve the Schr?dinger equation of a single electron,the energy levels and electron wave function distributions are obtained.Based on this,the simulation analysis of the existing quantum cascade laser is carried out to verify the effectiveness of the method,and on the premise of ensuring the accuracy of the calculation,the calculation speed can be increased to about 3 times by the finite difference method.Furthermore,particle swarm optimization is used to optimize the simulation model of quantum cascade laser,calculate the electronic temperature of each energy level,simulate the output characteristics of quantum cascade laser,analyze and discuss the influence of the electronic temperature of each energy level on the output characteristics of quantum cascade laser.The threshold current density of the quantum cascade laser obtained by simulation is 1.82k A/cm~2,and the difference between the measured power and the simulated power is only about 50m A.The model is more optimized in the experimental correlation and guidance,which can lay an important foundation for further theoretical study of all-optical modulation mechanism of quantum cascade laser.Experimentally,an experimental device was constructed to evaluate the all-optical modulation of quantum cascade lasers based on the photoluminescence spectroscopy,and the optimal modulation wavelength was determined to be 1560nm and the spot position to be 5.045mm,which could be used to optimize the all-optical modulation of quantum cascade lasers.At the same time,the experimental system of direct absorption spectrum based on quantum cascade laser is established.Based on this,the experimental research of NO gas detection is carried out.In 1000 ns,the direct absorption spectrum of NO gas was obtained,and the detection curve of NO gas concentration in the direct absorption spectrum was measured.The quantitative measurement of NO gas concentration was carried out.The minimum absorbance was 0.05345,and the corresponding gas concentration was 6.47ppm.