Multi-kW high-efficiency high-filling-factor 870nm and 940nm QCW semiconductor diode laser bar for inertial fusion energy applications

We present recent progress of semiconductor quasi-continuous-wave diode laser bars at 870nm and 940nm for inertial fusion energy applications. With optimization of epitaxial structure, chip layout, wafer processing and facet passivation, diode laser bars with 75% filling factor and 4.0mm cavity length at both 870nm and 940nm were successful manufactured with single junction and dual junctions. From single junction bar, more than 1kW QCW optical power with close 60% E/O efficiency is demonstrated; for double junction bar, 1.8kW optical power with more than 60% E/O efficiency is demonstrated at 870nm, and 2.7kW optical power with 52% E/O efficiency is achieved at 940nm. We also show the pathway to achieve even higher E/O efficiency by further optimization. We also present the simulated results of using those high-power bar a in high density QCW stack with 36kW peak power and 19.8kW/cm² optical power density based on single junction bar and up to 80kW peak power stack and 44.2kW/cm² optical power density based on double junction bar.