Recent results of blue and green InGaN laser diodes for laser projection

Stephan Lutgen, Dimitri Dini, Ines Pietzonka, Soenke Tautz, Andreas Breidenassel, Alfred Lell, Adrian Avramescu, Christoph Eichler, Teresa Lermer, Jens Müller, Georg Bruederl, Alvaro Gomez, Uwe Strauss, Wolfgang G. Scheibenzuber, Ulrich T. Schwarz, Bernhard Pasenow, Stephan Koch

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

42 Scopus citations

Abstract

Mobile laser projection is of great commercial interest. Today, a key parameter in embedded mobile applications is the optical output power and the wall plug efficiency of blue and green lasers. We report on improvements of the performance of true blue riedge waveguide InGaN lasers at 452nm with cw-output power up to 800mW in overstress and mono mode operation up to 500mW in a temperatures range of 20°C to 80°C. We succeeded in high and almost temperature independent wall plug efficiencies >20% at stable output power levels from 200 to 500mW in cw-operation. Due to several improvements of our blue laser diodes we now estimate life times is in the order of 40khrs for 80mW output power in cw-operation at 40°C. Additional overstress degradation tests at power levels up to 200mW show a strong dependency of lifetime with output power. Furthermore, we present pioneering results on true green InGaN laser diodes on c-plane GaN-substrates. The technological challenge is to achieve In-rich InGaN-quantum wells with sufficiently high material quality for lasing. We investigated the competing recombination processes below laser threshold like nonradiative defect recombination by electro-optical measurements, such confirming that low defect densities are essential for stimulated emission. A model for alloy fluctuations in In-rich InGaN-MQWs based on spectral and time resolved photoluminescence measurements yields potential fluctuations in the order of E0=57meV for our blue laser diodes. To get a closer insight into the physics of direct green InGaN-Laser we investigated the inhomogeneous broadening of experimentally measured gain curves via Hakki-Paoli-measurements in comparison to calculated gain spectra based on microscopic theory showing the importance of strong LO-phonon coupling in this material system. Investigations of current dependent gain measurements and calculations yield a factor of 2 higher inhomogeneous broadening for our green lasers than for our blue laser diodes on c-plane GaN. Based on the improvements of the material quality and design we demonstrate true green InGaN-Laser in cw-operation at 522nm with more than 80mW output power on c-plane GaN. The combination of low laser threshold ∼60-80mA, high slope efficiency ∼0.65W/A and low operating voltage 6.9-6.4V of our green monomode RWG-Laser results in a high wall plug efficiency of 5-6% in a temperature range of 20-60°C.

Original languageEnglish (US)
Title of host publicationNovel In-Plane Semiconductor Lasers X
DOIs
StatePublished - Mar 31 2011
EventNovel In-Plane Semiconductor Lasers X - San Francisco, CA, United States
Duration: Jan 25 2011Jan 28 2011

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume7953
ISSN (Print)0277-786X

Other

OtherNovel In-Plane Semiconductor Lasers X
CountryUnited States
CitySan Francisco, CA
Period1/25/111/28/11

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Keywords

  • GaN
  • RWG laser
  • Semiconductor laser

ASJC Scopus subject areas

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

Cite this

Lutgen, S., Dini, D., Pietzonka, I., Tautz, S., Breidenassel, A., Lell, A., Avramescu, A., Eichler, C., Lermer, T., Müller, J., Bruederl, G., Gomez, A., Strauss, U., Scheibenzuber, W. G., Schwarz, U. T., Pasenow, B., & Koch, S. (2011). Recent results of blue and green InGaN laser diodes for laser projection. In Novel In-Plane Semiconductor Lasers X [79530G] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 7953). https://doi.org/10.1117/12.874757