Investigation of the coherent combination of a 19-fiber laser beam characteristics to achieve a multi tens of kW at a distance of 10 km

Abstract

In this paper, we used a coherent beam combination to design a 50 kW high power laser beam for energy applications. Because of the strong environmental turbulence, degrade the coherent beam combination advantages, low turbulence level is considered. Combining elements are composed of 19 polarized single mode 3 kW high power fiber lasers where are arranged in the co- two centric hexagonal rings. Each of the fiber a lasers has a collimator with a 30 mm beam spot size output. We extended the transmitting range to z=10 km and the improved filling factor up to f=0.91. Therefore, power loss at the side lobes are minimized and resulted in the rise of combination efficiency to 88%, which is the highest published result. The central spot size radius on the target is R=5.9 cm, where indicate 0.45 kW/cm2 power density. Also, the effect of Phase errors of the combining elements at the far- field, which cause the ray intensity scattering from the center spot to the side lobes is investigated.

Keywords

• fiber laser
• coherent combining