The temperature dependence of key electro-optical characteristics for mid-infrared emitting quantum cascade lasers

Dan Botez*, Jae Cheol Shin, Sushil Kumar, Jeremy Kirch, Chun Chieh Chang, Luke J. Mawst, Igor Vurgaftman, Jerry R. Meyer, Alfredo Bismuto, Borislav Hinkov, Jerome Faist

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

30 Citations (Scopus)


The equations for the threshold-current density Jth, differential quantum efficiency ?d and maximum wallplug efficiency ηwp,max for quantum-cascade lasers (QCLs) have been modified for electron leakage and backfilling. We used a thermalexcitation model of "hot" injected electrons from the upper laser state to upper active-region energy states to calculate leakage currents. Then the calculated characteristic temperature T0 for Jth was found to agree well with experiment for both conventional and deep-well QCLs. The characteristic temperature T 1 for ηd was deduced to be due to both electron leakage and an increase in the waveguide-loss coefficient. For conventional mid-infrared QCLs ηwp,maxis found to be strongly temperature dependent which explains experimental data. By using a new concept: tapered active-region (TA), deep-well QCLs have been optimized for virtual suppression of the electron-leakage currents. In turn, at room temperature, for continuous-wave (CW)-operating, 4.5-5.0 μm-emitting TA QCLs we estimate the threshold current to decrease by ∼ 25 %, the active-region temperature rise at the ηwp,max point to decrease by ∼ 30 %, and the single-ended, ηwp,max value to become at least 22 %. Preliminary results from TA QCLs include T1 values as high as 454 K, over the 20-60 °C heatsink-temperature range.

Original languageEnglish
Title of host publicationNovel In-Plane Semiconductor Lasers X
Publication statusPublished - 2011
Externally publishedYes
EventNovel In-Plane Semiconductor Lasers X - San Francisco, CA, United States
Duration: 2011 Jan 252011 Jan 28

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceNovel In-Plane Semiconductor Lasers X
Country/TerritoryUnited States
CitySan Francisco, CA


  • Electron leakage
  • Mid-infrared
  • Quantum cascade lasers
  • Slope-efficiency characteristic temperature
  • Strain-compensated
  • Tapered active region
  • Threshold-current characteristic temperature
  • Wallplug efficiency

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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