High Efficiency 1.9 Kw Single Diode Laser Bar Epitaxially Stacked With a Tunnel Junction

We report on the development of a 940-nm diode laser bar based on epitaxially stacked active regions by employing a tunnel junction structure. The tunnel junction and the device parameters were systematically optimized to achieve high output and power conversion efficiency. A record quasi-continuous wave (QCW) peak power of 1.91 kW at 25 degrees C was demonstrated from a 1-cm wide bar with a 2-mm cavity length at 1 kA drive current (200 mu s pulse width and 10 Hz repetition rate). Below the onset of the thermal rollover, the slope efficiency was as high as 2.23 W/A. The maximum power conversion efficiency of 61.1% at 25 degrees C was measured at 300 A. Reducing the heatsink temperature to 15 degrees C led to a marginal increase in the peak power to 1.95 kW.