THz quantum cascade video

THz quantum cascade video

Operating principle

This video (mpg4, 23 MB) shows how a Quantum Cascade Laser (QCL) works. The first 10 seconds summarize the features of our nextnano software and the numerical methods we use, the remaining 20 seconds show the animated simulation results. At exactly 20 seconds, the QCL starts to lase: The electron density (figure on the right) shows the population inversion, i.e. the higher state has a larger (indicated in red color) electron population than the lower lasing state (green color).

The video shows calculated results of the

  • Local density of states ρ(x,E)
  • Energy resolved electron density n(x,E)
  • Energy resolved current density j(x,E)

as a function of applied bias.

Band structure engineering / Wave function engineering

The white line shows the conduction band edge profile. It is this profile that we have to engineer in order to optimize the QCL performance.


This video shows a GaAs/AlGaAs THz QCL. Within the FLASH project a design based on the Ge/SiGe material system will be developed. Animated videos of numerically calculated simulation results will help our researchers to find a working design more efficiently. Furthermore, within this project we will generate an animated video that can be used for educational purposes such as teaching students how a QCL works.