Filled aperture coherent beam combining using multi-plane light conversion and microcontroller-based hill climbing

Authors: Clément Jacquard, Claire Autebert, Pierre Vernaz-Gris, Tangi Le Guennic, Julien Bayol, Pu Jian, Guillaume Labroille

Cailabs, Rennes, FRANCE

Abstract

Coherent combination of laser beams is crucial for high-power laser development in various applications, including defense and communication systems. A filled-aperture coherent beam combiner is introduced, which includes polarization-maintaining fiber components, Electro-Optic Modulators, EDFA, a Multi-Plane Light Converter, and a feedback loop based on the Stochastic Parallel Gradient Descent algorithm. The SPGD algorithm allows precise control of the EOMs to achieve stable optical output power. The experimental results demonstrate the proposed approach achieves coherent combination of up to 6 input channels with high efficiency, negligible power loss duration, and precise control over thermal and mechanical perturbations. This technology is directly scalable for different wavelengths.