Multi-beam formation of a tiled fiber laser array with closed-loop control

Tiled fiber laser arrays have attracted significant attention for their potential in power scaling and mitigation of atmospheric turbulence. In recent years, the capability to form multiple beams has been highly desirable across a variety of applications. However, existing tiled laser arrays have been limited to generating a single combined beam owing to optimization-based control algorithms. We present a novel approach for multi-beam formation using a tiled fiber laser array with closed-loop steering control. A tagging laser is divided and coupled into each beamlet. By modulating the sequence of the tagging laser pulses and synchronizing a far-field camera, the pointing of each beamlet is directly measured and individually controlled. The beamlets are then organized in groups, and the beamlets in each group are combined to a common position in the far field. Multiple beams can be formed on demand through corresponding group configurations. An experimental system comprising seven beamlets and an adaptive fiber collimator array achieved the formation of one, two, and three beams using the proposed method. To the best of our knowledge, this is the first demonstration of closed-loop multi-beam formation using a tiled fiber laser array.