title: Two-dimensional diffractive coherent combining of 15 fiber amplifiers into a 600 W beam.
abstract: We demonstrate coherent beam combining using a two-dimensionally patterned diffractive optic combining element. Fifteen Yb-doped fiber amplifier beams arranged in a 3×5 array were combined into a single 600 W, M²=1.1 output beam with 68% combining efficiency. Combining losses under thermally stable conditions at 485 W were found to be dominated by spatial mode-mismatch between the free space input beams, in quantitative agreement with calculations using the measured amplitude and phase profiles of the input beams.
authors.affiliation: Northrop Grumman Aerospace Systems, Redondo Beach, California 90278, USA. peter.thielen@ngc.com
authors.forename: Peter A
authors.initials: PA
authors.lastname: Thielen
authors.forename: James G
authors.initials: JG
authors.lastname: Ho
authors.forename: David A
authors.initials: DA
authors.lastname: Burchman
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Goodno
authors.forename: Joshua E
authors.initials: JE
authors.lastname: Rothenberg
authors.forename: Michael G
authors.initials: MG
authors.lastname: Wickham
authors.forename: Angel
authors.initials: A
authors.lastname: Flores
authors.forename: Chunte A
authors.initials: CA
authors.lastname: Lu
authors.forename: Benjamin
authors.initials: B
authors.lastname: Pulford
authors.forename: Craig
authors.initials: C
authors.lastname: Robin
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Sanchez
authors.forename: D
authors.initials: D
authors.lastname: Hult
authors.forename: K B
authors.initials: KB
authors.lastname: Rowland