Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 36: Poster III
HL 36.37: Poster
Mittwoch, 27. Februar 2008, 16:30–19:00, Poster D
Lateral Mode Behaviour of Broad Ridge 405 nm (Al,In)GaN Laser Diodes: Experiment and Simulation — •Stephan Rogowsky1, Dominik Scholz1, Harald Braun1, Ulrich T. Schwarz1, Ansgar Laubsch2, Georg Brüderl2, and Uwe Strauß2 — 1NWF II - Physik, Universität Regensburg — 2Osram Opto Semiconductors GmbH
In the (Al,In)GaN material system lateral ground mode operation of ridge waveguide laser diodes (LDs) is limited to narrow ridge widths up to a few micrometers. For broader ridge LDs, which are inevitable for high output power applications, filaments or higher order lateral modes appear, which influence the far-field beam quality. We investigate the lateral profile of the optical laser mode in the waveguide experimentally and theoretically. We get our experimental results from time resolved scanning near-field optical microscopy (SNOM) measurements on pulsed electrically driven LDs. We measure the number and the width of filaments as a function of ridge width and current density. We compare these experimental data with one-dimensional simulations of the lateral laser mode profile. In these simulations we include the carrier- and thermal-induced modifications of the ridge waveguide refractive index profile. Therefore the spatial resolved rate equations for carriers and photons are solved in a self-consistent loop, including the interaction with the optical mode in the modified refractive index profile. By this method we can simulate the shape of typical measured lateral mode profiles for different ridge widths and current densities with a consistent set of parameters for broad ridge (Al,In)GaN LDs.