Optimizing geometrical parameters of coherent beam combining in the near and far-field distance

Abstract

Determining the characteristics of the laser array to improve the performance of a laser system based on coherent beam combination (CBC) has continuously garnered interest. To this end, the parameters of the Gaussian beam waist, array shape, and distance between adjacent beams were studied and numerically investigated in this study. Consequently, the combined beam quality was compared for hexagonal, circular, and square arrays. The observing plane’s location was fixed at 10 km and varied from 0.25 to 10 km to investigate the effect of beam waist on combined beam quality in two modes (near and far field) using the power in the 5 cm bucket metric (PIB5cm). Furthermore, the average PIB5cm was investigated to determine all observing plane distances. The simulation results in two states of fixed and variable observing plane distances demonstrated that the hexagonal array has an advantage in attaining PIB5cm and higher combined beam quality. In addition, the quality of the combined beam degrades as the space between the beams increases. Moreover, the optimal beam waist and aperture diameter are independent of the array geometry and the vacancy between adjacent beams.