Higher power density limit at COMD in GaInP/AlGaInP in quantum dots than in wells

摘要

Quantum dots (QD) offer significant advantages over quantum wells (QW) as the active material in high power lasers. We have determined power density values at catastrophic optical mirror damage (COMD), a key factor limiting high power laser diode performance, for various QW and QD red and NIR emitting structures in the in the AlGaInP system. The devices used were 50 um oxide stripe lasers mounted p-side up on copper heatsinks operated pulsed. The COMD power density limit decreases as pulse length increases. At short pulse lengths the limit is higher in QD (19.1±1.1 MW/cm~2) than in QW devices (11.9±2.8 MW/cm~2 and 14.3±0.4 MW/cm~2 for two different spot sizes). We used the high energy Boltzmann tail of the spontaneous emission from the front facet to measure temperature rise to investigate the physical mechanisms (non-radiative recombination of injected carriers and reabsorption of laser light at the facet) leading to COMD and distinguish between the behaviour at COMD of QW and QD devices. Over the range 1× to 2× threshold current the temperature rise in the QW structures was higher. Scanning electron microscopy showed a difference between the QD and QW lasers in the appearance of the damage after COMD.