Designs On GaAs/AlGaAs Quantum Cascade Lasers

The quantum cascade laser(QCL) is an excellent example of how quantum engineering can be used to conceive efficient devices and emitters in the mid-far-infrared. The study and the design of QCLs have important theoretical and practical value which are not only applicable to pollution monitoring and laser spectroscopy,but also to medical,communication and photodetector.Since their first demonstration, QCLs have been devised to work in a wide range of wavelengths and temperatures, by exploiting different designs,but always in the same material system:InP/GaInAs/AlInAs. Only recently the QCL concepts were successfully implemented into a GaAs/AlGaAs heterostructure.This thesis gives a brief overview of the history and developments of QCLs and designs the QCL based on material system of GaAs/AlGaAs. Results are summarized as follows:1.This paper describes the numerical solution of the Schrodinger equation through using programming language matlab to slove the equation. In addition, we derive the transition rate equations and obtain the population inversion conditions.2.In this article, we describe the different properties among different material systems and we give the design of the QCL based on Al0.3Ga0.7As material system which has the triple well active regions and the lasing wavelength of 18.3/μm. Our design of the active region includes the thickness of the active region unit, the barrier height, well width, barrier width and the selection of the bias.3.We calculate the intrasubband impurity scattering times and the intersubband scattering times of the QCL based on Al0.3Ga0.7As material system which has the triple well active regions and the lasing wavelength of 18.3μm and verify the achievement of population inversion conditions.