title: Perturbative analysis of coherent combining efficiency with mismatched lasers.
abstract: Coherent combining efficiency is examined analytically for large arrays of non-ideal lasers combined using filled aperture elements with nonuniform splitting ratios. Perturbative expressions are developed for efficiency loss from combiner splitting ratios, power imbalance, spatial misalignments, beam profile nonuniformities, pointing and wavefront errors, depolarization, and temporal dephasing of array elements. It is shown that coupling efficiency of arrays is driven by non-common spatial aberrations, and that common-path aberrations have no impact on coherent combining efficiency. We derive expressions for misalignment losses of Gaussian beams, providing tolerancing metrics for co-alignment and uniformity of arrays of single-mode fiber lasers.
authors.affiliation: Northrop Grumman Aerospace Systems, One Space Park, R1-1184D, Redondo Beach, California 90045, USA. gregory.goodno@ngc.com
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Goodno
authors.forename: Chun-Ching
authors.initials: CC
authors.lastname: Shih
authors.forename: Joshua E
authors.initials: JE
authors.lastname: Rothenberg