High-power GaAs-based semiconductor lasers are the most efficient source of energy for converting electrical into optical power. 940nm diode lasers are used directly or as pump sources for Yb:YAG solid-state lasers, and are widely used in laser cladding and other fields. Improving electro-optic conversion efficiency and reliable output power are urgent requirements for current research hotspots and industrial laser systems. In this paper, we use an asymmetric epitaxial structure of InGaAs/AlGaAs, which reduces the optical loss and resistance, and adopt better cavity surface technology to present 940nm 1-cm quasi-continuous micro-channel cooling (MCC) laser bars. The lasers are tested under a high duty cycle of 9.6% (600us,160Hz) at 25°C with output power of 660.05W, electro-optic conversion efficiency of 64.71% at 600A and slope efficiency of 1.16 W/A. The peak efficiency reaches 72.4%. The increased efficiency results from a lower threshold current and a lower series resistance. Furthermore, the output power of 1025W (1000A) has been confirmed at a duty cycle of 4% (400us,100Hz). © 2019 SPIE.