Temporal coherence effects on target-based phasing of laser arrays

This paper studies how temporal coherence (in particular, linewidth broadening introduced to suppress stimulated Brillouin scattering) affects target-based phasing of fiber laser arrays. A radio-frequency modulated array whose elements are fed by a broadband laser source phasing on a remote step target is theoretically analyzed. An expression for the detector plane irradiance, ultimately used to phase the array on the target, is derived and discussed in detail. Simulation results of a seven-element hexagonal array phasing on a distant step target with scattering surfaces separated by many coherence lengths are presented to validate the theoretical findings.