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Gallium nitride laser diodes with integrated absorber: On the dynamics of self-pulsation

: Holc, K.; Lükens, G; Weig, T.; Köhler, K.; Wagner, J.; Schwarz, U.T.


Physica status solidi. C 11 (2014), No.3-4, pp.670-673
ISSN: 1610-1634
ISSN: 1610-1642
ISSN: 1862-6351
International Conference on Nitride Semiconductors (ICNS) <10, 2013, Washington/DC>
Journal Article, Conference Paper
Fraunhofer IAF ()
nitride laser diodes; short pulses; picosecond pulses; multi-section laser diodes

The dynamics of self-pulsation in monolithic multi segment GaN-based laser diodes (LDs) with integrated absorber, and operating at 410 nm is investigated. The bias-dependent modal absorption of the devices is determined by high resolution Hakki-Paoli gain spectroscopy. Using a streak camera detection system we measure the pulsation frequency, applying bias voltages up to -40 V to the absorber section of the multi segment LD. Under moderate reverse voltages, to approximately -15 V, the absorption features a quadratic dependence on the bias voltage with a clear minimum corresponding to the flat band conditions. In this regime we observe stabilized relaxation oscillations, with a pulse repetition rate which depends only on the current in the gain section, but not on the reverse bias in the absorber section. At higher reverse voltages a linear increase of the modal absorption is observed. There, the devices switch to the self-Q-switching regime which exhibits a linear decrease of the pulsation frequency with increasing reverse bias.