Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 36: Poster III
HL 36.36: Poster
Mittwoch, 27. Februar 2008, 16:30–19:00, Poster D
Influence of Optical Gain on the Spectral and Temporal Characteristics of 405 nm (Al,In)GaN Laser Diodes Grown on Different Substrates — •Bernd Schmidtke1, Tobias Meyer1, Harald Braun1, Ulrich T. Schwarz1, Désirée Queren2, Marc Schillgalies2, Stephan Lutgen2, and Uwe Strauß2 — 1NWF II - Physik, Universität Regensburg — 2Osram Opto Semiconductors GmbH
We investigate the spectral and temporal behaviour of violet (Al,In)GaN laser diodes (LDs) emitting at wavelengths of about 405 nm, grown on low dislocation density GaN substrate and on SiC substrate, respectively. LDs on GaN substrate show a broad spectrum with several longitudinal modes above threshold, whereas LDs on SiC substrate partially are lasing on a single longitudinal mode, depending on the driving current. With a high spectral resolution setup we measure the gain below threshold of each longitudinal mode, employing the Hakki-Paoli method. Measurements show a slightly fluctuation of gain for the modes of GaN substrate LDs, but a much higher fluctuation for LDs on SiC substrate. We carry out simulations of the longitudinal mode spectrum of (Al, In)GaN laser diodes using a rate equation model with nonlinear gain effects. Additionally the gain of each longitudinal mode was modified to take the fluctuations of the measured gain into account. With the respective amplitude of these gain fluctuations, the simulated spectra resemble the GaN or SiC substrate LD spectra.