Improving fiber coupling efficiency of free space optical communication using blind optimization wavefront correction

To improve the fiber-coupling efficiency of free space optical communication systems, an adaptive optics system based on blind optimization is suggested to correct wavefront aberrations caused by atmospheric turbulences. The system adopts no wavefront sensor. The aberrated signal is splitted into a photoelectric detector to calculate the coupling efficiency before it enters the receiver. The stochastic parallel gradient descent algorithm (SPGDA) is then used to adapt the micromachined deformable mirror to optimize the optical power coupled into the fiber, with the Strehl ratio, the estimation formula of coupling efficiency, as the objective function. Numerical results demonstrate that the coupling efficiency is improved from 6% to about 60%.