High-power highly reliable Al-free 940-nm diode lasers

Al-free diode lasers emitting at 940 nm having a broadened step-index waveg uide structure and a single active InGaAs quantum well have been realized b y MOVPE. The impact of waveguide thickness on device performance has been s tudied. The highest wall plug efficiency of about 60% has been obtained wit h diode lasers having a 1-mum-thick waveguide. Increasing the waveguide thi ckness to 1.5 mum resulted in record low degradation rates below 10(-5) h(- 1) for 3-W output power (100 mum stripe width). The same diode lasers showe d a good long-term reliability even at an output power of 4 W. The best bea m quality had diode lasers with a 2-mum-thick waveguide, at the expense of a reduced temperature stability.