Degradation behavior and thermal properties of red (650 nm) high-power diode single emitters and laser bars

J.W. Tomm^a, T.Q. Tien^a, M. Ziegler^a, F. Weik^a, B. Sumpf^b, M. Zorn^b, U. Zeimer^b and G. Erbert^b

^a Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Str. 2A, 12489 Berlin, Germany
^b Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany

Published in:
Proc. SPIE 6456 (2007) 645606.
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Abstract:
The degradation behavior of broad-area laser diodes and bars emitting at 650 nm under constant power operation is investigated. In addition to the increase in operation current the temperature of the laser facets was monitored using Raman spectroscopy. The formation of defects was studied using photocurrent spectroscopy while cathodoluminescence provided insight into the position of extended non-radiative defects at different stages of degradation. Although the facet does not show any visible alteration even for failed devices, its immediate vicinity appears to be the starting point of the observed gradual degradation effects. At the same time the local facet temperature is increased. The observed aging behavior is compared to the known degradation scenarios for devices emitting at 808 nm. In both cases there is a clear correlation between packaging-induced strain and observed degradation effects as demonstrated by the results obtained for bars. For the red devices a correlation between optical load and facet temperature exists which proves that here facet heating is indeed caused by re-absorption processes. Furthermore, the gradual degradation process is not accompanied by the creation of dark bands along 100 directions as observed earlier for 808 nm devices. The observed gradual degradation of the 650 nm devices is primarily accompanied by the formation of deep-level point defects, followed by the creation of macroscopic areas of reduced luminescence intensity. Packaging induced strains become important when gradual bar degradation is monitored at early stages.

Keywords:
650 nm, high-power diode laser, cm-bar, degradation, thermal analysis

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