Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 70: Devices II
HL 70.1: Vortrag
Mittwoch, 28. März 2012, 17:15–17:30, EW 015
(Al,In)GaN laser diodes — •Thomas Weig, Katarzyna Holc, Wilfried Pletschen, Klaus Köhler, Joachim Wagner, and Ulrich Schwarz — Fraunhofer Institute for Applied Solid State Physics IAF, Tullastraße 72, 79108 Freiburg, Germany, www.iaf.fraunhofer.de
We develop violet-blue (Al,In)GaN double heterostructure laser diodes (LD). The single section, ridge waveguide LDs show threshold currents around 60 mW and slope efficiencies greater than 1 W/A in continuous wave (cw) operation. The internal losses are estimated by Hakki-Paoli gain measurements to be smaller than 25 cm−1. Laser dynamics and charge carrier lifetime are investigated with the help of a Streak-camera.
For picosecond pulse generation we also design multi-section InGaN LDs. The absorber section is placed at the end or in the center of the LD structure along the ridge, and is negatively biased. We observe self-pulsation in the GHz frequency range. The physical mechanism of this self-pulsation is in our case a stabilization of the relaxation oscillations which were observed in the single section LDs. By tuning the length of the driving current pulse we achieve optical pulses in the picosecond regime with arbitrary repetition rates from single shots to GHz by gain switching.