Improved Beam Quality of Coherently Combined Angled-Grating Broad-Area Lasers

We improve the beam quality and performance of coherently combined angled-grating broad-area lasers through current/gain confinement. We show that the nonuniform current/gain distribution in our previous lasers excites the second-order Bragg mode and degrades the beam quality. Ion implantation is used to provide a more uniform current distribution by confining the injected current within the grating area. The far-field measurement result shows that the near-diffraction-limited single-lobe envelope is obtained. Smaller threshold and larger slope efficiency are observed in the L-I curve as well.