Limitations to peak continuous wave power in high power broad area single emitter 980 nm diode lasers

Micro-channel cooling of 975nm single emitter broad area lasers has largely eliminated current heating as a power limitation. Instead, the peak achievable power is limited by high-current driven minority carrier accumulation in the waveguide. In order to enable higher powers, the copper carrier was replaced with a water-cooled microchannel heatsink. In previous studies of broad area lasers under short-pulse condition, rollover was also observed, even in the absence of current heating. This was found to correlate with minority carrier accumulation in the waveguide layer. Such accumulation can be observed experimentally via studies of the spontaneous emission. Carriers in the waveguide recombine and emit light in all directions - such emission can be separated spatially from stimulated (lasing) emission by measurements at a wide angle. In these devices, we also observe such carrier accumulation in the waveguide layers and such accumulation may be due to fundamental phonon-loss mechanisms.