Implant-Defined 3 $\times$ 3 In-Phase Coherently Coupled Vertical Cavity Surface Emitting Lasers Array

Two-dimensional in-phase coherently coupled vertical cavity surface emitting laser (VCSEL) array with high beam quality was fabricated by proton implantation. Indium-tin-oxide (ITO) current spreading layer was employed to improve the uniformity of the injection current. This makes a coherent array to operate in in-phase mode even in a relatively larger scale. The appropriate thickness of ITO curre...