Power in bucket enhancement in tiled-aperture coherent beam combining through inducing spatial chirp

Spatial gaps between sub-beams in achieving high-peak-power lasers with tiled-aperture based coherent beam combining (Ta-CBC) give rise to relatively strong sidelobes and impair the power in bucket (PIB) at far-field. To address the aforementioned issue, spatial chirp is employed in this paper to fill the gaps and further enhance PIB. With two sub-beams, both simulations and experiments indicate that PIB can be enhanced by about 1.8 times with spatial chirp when the gap-beam width ratio is 0.2. Furthermore, a PIB enhancement ratio of 1.8 is achieved when four sub-beams with a gap-beam width ratio of 0.05 in the simulation. In short, the spatial-chirp-assisted Ta-CBC method holds the potential in enhancing focal laser intensity during achieving tens to hundreds of petawatt (PW) lasers.