Study of lateral brightness in 20 μm to 50 μm wide narrow stripe broad area lasers

We present a design study of high power narrow stripe broad area diode lasers at 9xx-nm with contact stripe widths of 20 μm, 30 μm and 50 μm. The devices are deeply implanted with helium (He⁺) at the edges of the electrical contact, to reduce lateral current spreading and lateral carrier accumulation. All devices operate with a lateral beam parameter product (BPP) below 2 mm x mrad, but differ strongly in linear brightness and maximal output power. The linear brightness can reach up to 5.6 W/mm x mrad from a 20 μm wide stripe at an optical output power of 4 W. However, at higher output power the beam quality degrades strongly for 20 μm wide stripes, making stripe width of 30 μm or 50 μm more beneficial for high brightness at P ≥ 5 W.