[TuP3D] D. Photonic devices and related technologies

[TuP3D-15] Reduced Lateral Divergence in 1550 nm Broad-Area Laser Diodes

〇Niklas Kanold¹, Martin Möhrle¹, Martin Schell¹ (1. Fraunhofer Inst. of Telecommunications, Heinrich-Hertz-Institut, HHI (Germany))

As indicated by simulations, the lateral divergence of broad-area lasers can be reduced by the suppression of the respective higher order modes in the cavity. This is achieved for a 1550 nm large optical cavity (LOC) structure in two different approaches. While the mode filtering via reduction of the backside width of the cavity results in a reduction of 17 % for the lateral divergence angle (FWHM) at the investigated working conditions, it comes with the tradeoff of a reduction of the maximum optical output power of 16 %. This can be mainly attributed to the reduced active area resulting in an increased series resistance and decreased heat dissipation capability. The second approach is the reduction of the width of the trench that confines the pumped active area of the laser. For a reduction of this parameter from 30 µm down to 1 µm, a reduction of the lateral divergence angle of 30 % can be observed. At the same time the maximum optical output power is reduced by only around 6 %. This paves the way for easier beam shaping and thus enables improvements of performance especially in the field of material processing and imaging.