title: Deep turbulence effects mitigation with coherent combining of 21 laser beams over 7 km.
abstract: We demonstrate coherent beam combining and adaptive mitigation of atmospheric turbulence effects over 7 km under strong scintillation conditions using a coherent fiber array laser transmitter operating in a target-in-the-loop setting. The transmitter system is composed of a densely packed array of 21 fiber collimators with integrated capabilities for piston, tip, and tilt control of the outgoing beams wavefront phases. A small cat's-eye retro reflector was used for evaluation of beam combining and turbulence compensation performance at the target plane, and to provide the feedback signal for control of piston and tip/tilt phases of the transmitted beams using the stochastic parallel gradient descent maximization of the power-in-the-bucket metric.
authors.forename: Thomas
authors.initials: T
authors.lastname: Weyrauch
authors.forename: Mikhail
authors.initials: M
authors.lastname: Vorontsov
authors.forename: Joseph
authors.initials: J
authors.lastname: Mangano
authors.forename: Vladimir
authors.initials: V
authors.lastname: Ovchinnikov
authors.forename: David
authors.initials: D
authors.lastname: Bricker
authors.forename: Ernst
authors.initials: E
authors.lastname: Polnau
authors.forename: Andrey
authors.initials: A
authors.lastname: Rostov