Beam quality and power scalability of fiber laser array in a S-F cavity

Coherent beam combination (CBC) of laser array has the potential to solve the power limitation in single fiber laser as well as maintaining good beam quality. Fiber laser array in self-Fourier (S-F) cavity presents a promising approach for CBC due to its compactness, simplicity, ease of alignment, and stability in phase locking, which have been under intense research recently. In this paper, we perform a system level analysis on the fiber laser array in S-F cavity. Analytical analysis on the beam quality and power scalability will be presented. By numerical calculation it is found that the total power contained in the laser array has linear relationship with the laser numbers. The total output power P of N laser in a S-F cavity can be expressed as P ∝ 0.4× N. It is also revealed that power encircled in the diffraction-limited bucket will not increase with N, adding more laser elements in the laser cavity will result in more laser power contained in the sidelobes in the far-field pattern.