title: Automated co-alignment of coherent fiber laser arrays via active phase-locking.
abstract: We demonstrate a novel closed-loop approach for high-precision co-alignment of laser beams in an actively phase-locked, coherently combined fiber laser array. The approach ensures interferometric precision by optically transducing beam-to-beam pointing errors into phase errors on a single detector, which are subsequently nulled by duplication of closed-loop phasing controls. Using this approach, beams from five coherent fiber tips were simultaneously phase-locked and position-locked with sub-micron accuracy. Spatial filtering of the sensed light is shown to extend the control range over multiple beam diameters by recovering spatial coherence despite the lack of far-field beam overlap.
authors: Northrop Grumman Aerospace Systems, One Space Park, R1-1184D, Redondo Beach, California 90278, USA. gregory.goodno@ngc.com
authors: Gregory D
authors: GD
authors: Goodno
authors: S Benjamin
authors: SB
authors: Weiss