The generation and verification of Bessel-Gaussian beam based on coherent beam combining

We propose a method to generate Bessel-Gaussian (BG) beam by Gaussian beam array where beamlets are arranged along a circle. The phase difference between adjacent beamlets is a constant, and the total phase increment is equal to 2πl (l is integer). Based on coherent superposition of the Gaussian beam array, we proved that the vortex beam obtained by the coherent beam combining (CBC) scheme is Bessel Gaussian beam when the number of Gaussian beams is sufficiently large. The experimental results show that a combined BG (CBG) beam, despite existing side lobe, can still be generated by limited number of Gaussian beams. Therefore, the feasibility of generating vortex (CBG) beam by the CBC scheme has been proved theoretically and experimentally. Moreover, a CBG beam with expected beam radius is generated by controlling the ring radius of Gaussian beam array. Our theoretical predictions match with the experimental results. This work could provide a theoretical basis for practical implementation of generating vortex beams by CBC technology.