High wall-plug efficiency diode lasers with an Al-free active region at 975 nm

In this work, we present high-wall plug efficiency (WPE) diode lasers at 975 nm, which are based on an Al-free active region. On a 2 mm x 100 μm laser, we have obtained a high maximum wall-plug efficiency of 69% at 10°C CW. Based on the same structure, we have realised a 1-cm bar, mounted on an active submount, and which delivers 70 W CW, together with 67% wall-plug efficiency. By improving the laser structure, we have obtained a higher WPE of 70% on an uncoated 2 mm x 100 μm broad area laser. We also present a new structure with a reduced fast-axis far-field of only 34° at 1/e2.