Highly efficient coherent beam combining of tiled aperture arrays using out-of-phase pattern

We propose a simple, highly scalable, and very efficient scheme for coherent combining of tiled aperture arrays. The scheme relies on changing the beam phasing paradigm from the commonly used in-phase pattern to the out-of-phase pattern (interleaved 0/π phases in the neighboring channels) and using an additional simple combining stage (a beamsplitter). In a proof-of-concept experiment with a one-dimensional fiber array, we achieved 89% of the power in the main combined beam. In numerical modeling, we found optimal conditions leading to 98% efficiency for an unlimited number of channels and arbitrary small initial aperture fill factors. The scheme is highly resistant to the effect of sub-aperture clipping and suitable for combining ultrashort pulses.