title: Active coherent beam combining of diode lasers.
abstract: We have demonstrated active coherent beam combination (CBC) of up to 218 semiconductor amplifiers with 38.5 W cw output using up to eleven one-dimensional 21-element individually addressable diode amplifier arrays operating at 960 nm. The amplifier array elements are slab-coupled-optical-waveguide semiconductor amplifiers (SCOWAs) set up in a master-oscillator-power-amplifier configuration. Diffractive optical elements divide the master-oscillator beam to seed multiple arrays of SCOWAs. A SCOWA was phase actuated by adjusting the drive current to each element and controlled using a stochastic-parallel-gradient-descent (SPGD) algorithm for the active CBC. The SPGD is a hill-climbing algorithm that maximizes on-axis intensity in the far field, providing phase locking without needing a reference beam.
authors.affiliation: Massachusetts Institute of Technology, Lincoln Laboratory, Lexington, Massachusetts 02420, USA. s.redmond@ll.mit.edu
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Redmond
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Creedon
authors.forename: Jan E
authors.initials: JE
authors.lastname: Kansky
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Augst
authors.forename: Leo J
authors.initials: LJ
authors.lastname: Missaggia
authors.forename: Michael K
authors.initials: MK
authors.lastname: Connors
authors.forename: Robin K
authors.initials: RK
authors.lastname: Huang
authors.forename: Bien
authors.initials: B
authors.lastname: Chann
authors.forename: Tso Yee
authors.initials: TY
authors.lastname: Fan
authors.forename: George W
authors.initials: GW
authors.lastname: Turner
authors.forename: Antonio
authors.initials: A
authors.lastname: Sanchez-Rubio