QCL_Simulation_Package solves the conduction band potential edge profile, quantized energy levels, and associated electron wavefunctions for a quantum cascade laser (QCL). Determining these quantities is a critical step in designing QCLS [1]. In a complete QCL design, one must also design the optical waveguide to ensure sufficient optical overlap of the lasing mode with the electrons in the inverted layers of the quantum cascade structures [1]. The approach that we used is conventional, and more information on the equations that we solve and the algorithms that we used to solve them may be found in [2, 3].

To use this simulation package, one must download it from the website www.umbc.edu/photonics/software and unzip into a local directory. A file has to be created with the layer thicknesses, material type, composition, and doping density of the QCL. This file has to be stored in folder ‘Input.’ The name of this input file and the applied electric field to the structure have to be used in the file ‘main.m.’ Once main.m matlab program is run, conduction band edge profile, quantized energy levels, and associated wavefunctions are solved and stored in folder ‘Output.’ The results will be plotted by the function ‘plotQCL.’ By changing the last three FLAGs of function plotQCL(Psi, E, Vx, x, wavefunc_flag, modulisqr_flag, modulisqrtrunc_flag), plots with wavefunctions, moduli-squared wavefunctions, and truncated moduli-squared wavefunctions are obtained. An example of how QCL structures should be written in the appropriate format for this package has been given in the ‘Input’ folder. The necessary descriptions have been given in the ‘read me.txt’ file. For any other question, please write to anisuzzaman@umbc.edu.

This simulation package has been developed by Muhammad Anisuzzaman Talukder, who is a member of Professor Curtis Menyuk’s research group. Mr. Talukder is a PhD candidate of Electrical Engineering in University of Maryland Baltimore County. It was developed with support from the MIRTHE Engineering Research Center as part of its outreach activities and to support ongoing research efforts both inside and outside of MIRTHE.

REFERENCES
1. C. Gmachl, F. Capasso, D. L. Sivco, and A. Y. Cho, “Recent Progress in quantum cascade lasers and applications,” Rep. Prog. Phys. 64, 1533–1601, 2001.
2. J. Faist, F. Capasso, C. Sirtori, and D. L. Sivco, “Intersubband transitions in quantum wells: Physics and Device Applications II,” in Quantum Cascade Lasers, edited by H. C. Liu and F. Capasso, Academic Press, 2000.
3. P. Harrison, Quantum Wells, Wires, and Dots, Wiley, 2005.