Short injector quantum cascade lasers

Kale J. Franz, Peter Q. Liu, James J.J. Raftery, Matthew D. Escarra, Anthony J. Hoffman, Scott Sheridan Howard, Yu Yao, Yamac Dikmelik, Xiaojun Wang, Jen Yu Fan, Jacob B. Khurgin, Claire F. Gmachl

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


We report our study on the effects of shortened quantum cascade (QC) laser injector regions. While conventional short-wavelength QC lasers typically have around seven or more injector region quantum wells, we investigate QC structures with three and two injector wells. Improvements in threshold currents, output powers, and wall-plug efficiencies are expected for fundamental reasons. At heat sink temperatures near 80 K, we observe threshold current densities less than 0.5 kA/cm2, nearly 4 W peak output power, and wall-plug efficiencies in excess of 20%. At room temperature, we see threshold current densities around 2.3 kA/cm2, output powers in excess of 1 W, and wall-plug efficiencies around 7.6%. We also observe new effects in midinfrared QC lasers, such as a pronounced negative differential resistance, pulse instabilities, and multiple and varied turn-off mechanisms. These effects result from the greatly abbreviated injector regions with highly discrete states.

Original languageEnglish (US)
Article number5420227
Pages (from-to)591-600
Number of pages10
JournalIEEE Journal of Quantum Electronics
Issue number5
StatePublished - 2010

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


  • Midinfrared
  • Negative differential resistance
  • Quantum cascade (QC) laser
  • Short injector


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