Phase locking of an array of three fiber lasers by an all-fiber coupling loop

Constructing a phase-locking array of fiber lasers by an all-fiber coupling loop is presented, and the loop is composed of multiple 2x2 fiber couplers which are connected with the output ends of component fiber lasers of the array. Due to the mutual injection locking among the fiber lasers by the coupling loop, they can achieve the phase-locking states and then are coherently combined in the far field. Phase locking of an array of three fiber lasers with this configuration has been demonstrated experimentally, and obvious interference patterns and stable coherent output have been observed.