Incoherent Combining of High-Power Fiber Lasers for Directed-Energy Applications

摘要

High-power fiber lasers can be incoherently combined to form the basis of a directed high-energy laser system that is highly efficient, compact, robust, low maintenance, and has a long operating lifetime. This approach has a number of advantages over other beam-combining methods. We present results of the first field demonstration of incoherent beam combining using kilowatt-class, single-mode fiber lasers. The experiment combined four fiber lasers using a beam director consisting of individually controlled steering mirrors. Propagation efficiencies of ～ 90%, at a range of 1.2 km, with transmitted continuous wave (CW) power levels of 3 kW were demonstrated in moderate atmospheric turbulence. We analyze the propagation of combined single-mode and multi-mode beams in atmospheric turbulence and find good agreement between theory, simulations, and experiments.