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Portrait of Andreas Wacker. Photo: Kennet Ruona

Andreas Wacker


Portrait of Andreas Wacker. Photo: Kennet Ruona

An indirectly pumped terahertz quantum cascade laser with low injection coupling strength operating above 150 K


  • S. G. Razavipour
  • E. Dupont
  • S. Fathololoumi
  • C. W. I. Chan
  • Martin Franckie
  • Z. R. Wasilewski
  • G. Aers
  • S. R. Laframboise
  • Andreas Wacker
  • Q. Hu
  • D. Ban
  • H. C. Liu

Summary, in English

We designed and demonstrated a terahertz quantum cascade laser based on indirect pump injection to the upper lasing state and phonon scattering extraction from the lower lasing state. By employing a rate equation formalism and a genetic algorithm, an optimized active region design with four-well GaAs/Al0.25Ga0.75As cascade module was obtained and epitaxially grown. A figure of merit which is defined as the ratio of modal gain versus injection current was maximized at 150 K. A fabricated device with a Au metal-metal waveguide and a top n(+) GaAs contact layer lased at 2.4 THz up to 128.5 K, while another one without the top n(+) GaAs lased up to 152.5 K (1.3 (h) over bar omega/k(B)). The experimental results have been analyzed with rate equation and nonequilibrium Green's function models. A high population inversion is achieved at high temperature using a small oscillator strength of 0.28, while its combination with the low injection coupling strength of 0.85 meV results in a low current. The carefully engineered wavefunctions enhance the quantum efficiency of the device and therefore improve the output optical power even with an unusually low injection coupling strength. (C) 2013 AIP Publishing LLC.


  • Mathematical Physics
  • NanoLund: Center for Nanoscience

Publishing year





Journal of Applied Physics





Document type

Journal article


American Institute of Physics (AIP)


  • Condensed Matter Physics




  • Modeling Quantum Cascade Lasers: the Challenge of Infra-Red Devices


  • ISSN: 0021-8979