title: High power compatible internally sensed optical phased array.
abstract: The technical embodiment of the Huygens-Fresnel principle, an optical phased array (OPA) is an arrangement of optical emitters with relative phases controlled to create a desired beam profile after propagation. One important application of an OPA is coherent beam combining (CBC), which can be used to create beams of higher power than is possible with a single laser source, especially for narrow linewidth sources. Here we present an all-fiber architecture that stabilizes the relative output phase by inferring the relative path length differences between lasers using the small fraction of light that is back-reflected into the fiber at the OPA's glass-air interface, without the need for any external sampling optics. This architecture is compatible with high power continuous wave laser sources (e.g., fiber amplifiers) up to 100 W per channel. The high-power compatible internally sensed OPA was implemented experimentally using commercial 15 W fiber amplifiers, demonstrating an output RMS phase stability of λ/194, and the ability to steer the beam at up to 10 kHz.
authors.forename: Lyle E
authors.initials: LE
authors.lastname: Roberts
authors.forename: Robert L
authors.initials: RL
authors.lastname: Ward
authors.forename: Samuel P
authors.initials: SP
authors.lastname: Francis
authors.forename: Paul G
authors.initials: PG
authors.lastname: Sibley
authors.forename: Roland
authors.initials: R
authors.lastname: Fleddermann
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Sutton
authors.forename: Craig
authors.initials: C
authors.lastname: Smith
authors.forename: David E
authors.initials: DE
authors.lastname: McClelland
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Shaddock