Phase and coherence extraction from an implant-defined photonic crystal VCSEL array

Electronically steerable laser sources have applications in diverse areas, such as optical display, free space communications, LIDAR, and illumination. Electronic beam steering using vertical cavity surface emitting lasers (VCSELs) has the advantages of system robustness, radiation hardness, reduced steering time, and energy efficiency. Recently, we demonstrated electronic steering of a single mode coherently coupled VCSEL array [1]. The leaky-mode VCSEL array [2, 3] utilizes a photonic crystal pattern to achieve in-phase operation [4], where a variable phase change between elements can be controlled with current injection to achieve steering [5]. In this work we experimentally extract the phase shift that induces the beam steering and its dependence on injection current. The induced phase change is determined from near and far-field profiles as a function of variable injection current into the array elements. These results will guide the optimization and control of electronic beam steering in leaky-mode VCSEL arrays.