Scalability and stability of a coherent fiber laser array using fiber couplers

Abstract

A coherent fiber laser array using fiber couplers is discussed. The array modes are analyzed and determined using coupled mode theory. A numerical analysis of the phase property for a 19-fiber array is performed and the results show that the array can achieve a quasi-in-phase state. The stability and the scalability of coherent combination are investigated by simulations via changing the fiber grating reflectivity, the pump parameter, and the cavity length. Considering the mutual coupling between fiber lasers and the mismatch among fiber lengths, we trace the relative phases between array elements and further provide the evidence of coherent combining for the 19-fiber array. With the increase in the fiber elements, although the system is required to operate at a lower grating reflectivity for achieving a stable laser output, the output power increases nonlinearly.