High-brightness kW QCW diode laser stacks with ultra-low pitches

Abstract

State-of-the-art QCW solid-state lasers are demanding ever higher brightness from the pump source-conduction cooled diode laser stacks. The intensity of a QCW vertical stack is limited by the peak power of each diode bar and the bar pitch. The minimum bar pitch of the existing laser diode stacks on the market is about 400um. In this paper, we present a unique vertical diode laser stack package design to achieve a bar pitch as low as 150um, which improves the intensity of the stack by nearly 3 times. Together with the state-of-art diode laser bar from Coherent, greater than 30kW/cm 2 peak power density is achieved from the emitting area of the vertical stack. The p-n junction temperature of the diode bars in the device under QCW operation is modeled with FEA software, as well as measured in this research. Updated reliability results for these diode laser stacks are also reported.