Investigation and comparison of optical gain spectra of (Al,In)GaN laser diodes emitting in the 375 nm to 470 nm spectral range

Ulrich T. Schwarz, Harald Braun, Kazunobu Kojima, Mitsuru Funato, Yoichi Kawakami, Shinichi Nagahama, Takashi Mukai

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

20 Citations (Scopus)


We measure gain spectra for commercial (Al,In)GaN laser diodes with peak gain wavelengths of 470 nm, 440 nm, 405 nm, and 375 nm, covering the spectral range accessible with electrical pumping. For this systematic study we employ the Hakki-Paoli method, i.e. the laser diodes are electrically driven and gain is measured below threshold current densities, The measured gain spectra are reasonable for a 2D carrier system and understandable when we take into account homogeneous and inhomogeneous broadening. While inhomogeneous broadening is almost negligible for the near UV laser diode, it becomes the dominant broadening mechanism for the longer wavelength laser diodes. We compare the gain spectra with two models describing the inhomogeneous broadening. The first model assumes a constant carrier density, while the second model assumes a constant quasi Fermi level. Both are in agreement with the experimental gain spectra, but predict very different carrier densities. We see our measurements as providing a set of standard gain spectra for similar laser diodes covering a wide spectral range which can be used to develop and calibrate theoretical manybody gain simulations.

Original languageEnglish
Title of host publicationNovel In-Plane Semiconductor Lasers VI
Publication statusPublished - 2007 May 24
Externally publishedYes
EventNovel In-Plane Semiconductor Lasers VI - San Jose, CA, United States
Duration: 2007 Jan 222007 Jan 25

Publication series

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


ConferenceNovel In-Plane Semiconductor Lasers VI
Country/TerritoryUnited States
CitySan Jose, CA


  • Hakki-Paoli method
  • InGaN laser diodes
  • Inhomogeneous broadening
  • Localized states
  • Optical gain

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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