Highly efficient coherent addition of N fiber lasers by use of fused fiber couplers has been demonstrated. Addition efficiencies of 93.6, 96.1, and 81.6% have been obtained for N=2, 4, and 8, respectively. The wavelengths satisfying constructive interference among the fields in the length-different N laser arms have the highest effective reflectivities and are selectively excited as a coherently-added single beam output. The characteristics of the Y-shape coupled array is investigated and the scalability of this method is discussed. A preliminary result of the coupling of two LDs is also reported.

© 2003 Optical Society of America

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