Download of QCL code used in

• J. Smiljanic, M. Zezelj, J. Radovanovic, V. Milanovic and I. E. Stankovic:
  "MATLAB-based Program for Optimization of Quantum Cascade Laser Active Region Parameters and Calculation of Output Characteristics in Magnetic Field"
  Comput. Phys. Commun. 185 (2014) 998
  doi: 10.1016/j.cpc.2013.10.025
• M. Zezelj, V. Milanovic, J. Radovanovic and I. E. Stankovic:
  "Influence of Interface Roughness Scattering on Output Characteristics of GaAs/AlGaAs Quantum Cascade Laser in a Magnetic Field" 
  J. Phys. D: Appl. Phys. 44 (2011) 325105
  doi: 10.1088/0022-3727/44/32/325105

A strong magnetic field applied along the growth direction of a quantum cascade laser (QCL) active region gives rise to a spectrum of discrete energy states, the Landau levels. By combining quantum engineering of a QCL with a static magnetic field, we can selectively inhibit/enhance non-radiative electron relaxation process between the relevant Landau levels of a triple quantum well and realize a tunable surface emitting device. An efficient numerical algorithm implementation is presented of optimization of GaAs/AlGaAs QCL region parameters and calculation of output properties in the magnetic field. Both theoretical analysis and MATLAB implementation are given for LO-phonon and interface roughness scattering mechanisms on the operation of QCL. At elevated temperatures, electrons in the relevant laser states absorb/emit more LO-phonons which results in reduction of the optical gain. The decrease in the optical gain is moderated by the occurrence of interface roughness scattering, which remains unchanged with increasing temperature. Using the calculated scattering rates as input data, rate equations can be solved and population inversion and the optical gain obtained. Incorporation of the interface roughness scattering mechanism into the model did not create new resonant peaks of the optical gain. However, it resulted in shifting the existing peaks positions and overall reduction of the optical gain.

About QCL

The QCL program provides an efficient numerical algorithm implementation for optimization of GaAs/AlGaAs QCL active region parameters and calculation of output properties in the magnetic field.
The optimization of the quantum cascade laser performance at selected wavelength is performed at entire free-parameters space using simulated annealing algorithm. The scattering rates are calculated in the presence and without magnetic field and used as coefficients in rate equations. The standard MATLAB procedures were used to solve iteratively this system of equations and obtain distribution of electron densities over electronic states.

Using QCL

The QCL program is developed using Matlab 2010 (R) and comes with a user-friendly graphical user interface (GUI). The code can be run on any platform supporting MATLAB (R) 2010 version or higher with 1GB RAM.
The machine must provide the necessary main memory which decreases roughly quadraticly with the increase of the magnetic field intensity.

The main m-file to run the program is QCL.m. In Matlab open the QCL.m file and click F5. This will display the interface.

Optimization time on Intel 3GHz processor is about 2×10⁴s. The calculation time of laser output properties for values set automatically in GUI is 5 × 10⁴s.