Kilowatt-class, 1-cm diode laser bars at 910-940 nm with improved power, conversion efficiency, and beam quality

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 P-opt and power-conversion-efficiency. E. The resulting ETAS bars containing 20 emitters with 395 mu m wide stripes and 4 mm long cavity, operate with the highest-to-date quasi-continuous-wave power (200 mu s, 10 Hz) P-opt = 1.9 kW, delivered from just one quantum well, with maximum eta(E) = 67% at THS = 298 K heat-sink temperature. High eta(E) = 62% is maintained at 1.0 kW and remains 55% at 1.5 kW. Even higher P-opt = 2.26 kW is achieved at a reduced T-HS = 203 K. At 203 K, maximum eta(E) climbs to 74% while maintaining a high eta(E) > 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 degrees without sacrificing P-opt and eta(E), reaching similar to 15 degrees at 1.8 kW at 298 K. Polarization purity also remains > 95% across the full measured range.