GaAs-based 1-cm bars based on extreme-triple-asymmetric (ETAS) epitaxial designs are presented. The investigated structure shows low optical loss and weak power saturation at high current allowing high output power Popt and power-conversion-efficiency ηΕ. The resulting ETAS bars containing 20 emitters with 395 μm wide stripes and 4 mm long cavity, operate with the highest-to-date quasi-continuous-wave power (200 μs, 10 Hz) Popt = 1.9 kW, delivered from just one quantum well, with maximum ηΕ = 67% at THS = 298 K heat-sink temperature. High ηΕ = 62% is maintained at 1.0 kW and remains 55% at 1.5 kW. Even higher Popt = 2.26 kW is achieved at a reduced THS = 203 K. At 203 K, maximum ηΕ climbs to 74% while maintaining a high ηΕ < 60% up to 2 kW, and reaches 55% at 2.26 kW. We also present progress in lateral bar layout, which is further optimized for narrow lateral beam divergence and evaluated for the first time up to 2 kA current. Experimental results show that lateral far field at 95% power can be lowered by 2-3° without sacrificing Popt and ηΕ, reaching ~15° at 1.8 kW at 298 K. Polarization purity also remains < 95% across the full measured range.
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