Gerchberg - Saxton algorithm: experimental realisation and modification for the problem of formation of multimode laser beams

An original method is proposed to calculate the formation of specified far-field intensity distributions by a bimorph mirror in the case of initial transverse-multimode beams. The method is based on the Gerchberg - Saxton algorithm with replacement of the phase function in the plane of the control element by a function that takes into account both the intensity and phase distributions of each mode. The numerical results on the formation of a beam with the third-order super-Gaussian intensity distribution from beams composed of two or four lowest transverse modes are discussed. The experimental results on using the conventional Gerchberg - Saxton algorithm to form a desired intensity distribution from single-mode laser beams using a liquid-crystal modulator are presented.