Carrier distribution, spontaneous emission and gain in self assembled quantum dot lasers

Peter M. Smowton, Emma J. Pearce, Julie Lutti, Dan R. Matthews, Huw D. Summers, Gareth M. Lewis, Peter Blood, Mark Hopkinson, Andrey Krysa

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

5 Scopus citations


We examine the mechanisms that lead to a low value of saturated modal gain in both 1μm emitting InGaAs based and ≈ 700nm emitting InP/GalnP quantum dot laser systems. We explain the observation that the value of the saturated modal gain increases as the temperature decreases using a simple model of the filling of the available dot and wetting layer states according to a Fermi-Dirac distribution. We show that it is the relatively large number of available wetting layer valence states and their proximity in energy to the dot states that limits the modal gain. We measure the population inversion factor for samples containing different numbers of layers of dots and for samples where the dots are grown in a quantum well (DWELL) and for dots grown in bulk layers of either GaAs or Al 0.15Ga 0.85As (non-DWELL). Comparison of this data with that calculated for a Fermi-Dirac distribution of carriers in the available states demonstrates that for most of the samples the carriers in the ground states of the quantum dots are not in thermal equilibrium with those in higher lying energy states - the excited states or wetting layer.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsC.F. Gmachl, D.P. Bour
Number of pages10
StatePublished - 2004
EventNovel In-Plane Semiconductor Lasers III - San Jose, CA, United States
Duration: Jan 26 2004Jan 28 2004


OtherNovel In-Plane Semiconductor Lasers III
Country/TerritoryUnited States
CitySan Jose, CA


  • Gain saturation
  • Laser diodes
  • Quantum dots

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics


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