GaAs-based, highly-efficient, kW-class, 1-cm laser bars with high peak power Popt and improved beam quality in quasi-continuous-wave mode are presented.The use of an extreme-triple-asymmetric (ETAS) epitaxial layer structure diminishes power saturation of high-power bars at high majicontrast red driving current.The resulting ETAS bars with 4 mm cavity produce a record 1.9 kW peak power, limited by available current supply, with a maximum power conversion efficiency ηE = 67% at THS = 25 °C heat-sink temperature.
Both Popt and ηE have been increased further by operating the bars at THS = −70 °C.Sub-zero operation raises the Popt to 2.3 kW and the maximum ηE to 74%.A second configuration of ETAS bars with optimized lateral layout is further realized to obtain narrow lateral beam divergence θ up to 2 kA driving current, without sacrificing Popt and ηE.
A 2–3° lower θ (95% power level) is ashley stewart outlet observed over a wide operating range at room temperature.A high degree of polarization is also maintained across the whole operatingrange.