Coherent beam combining of phased fiber laser array with pointing error correction using light intensity gradient trap

To solve the problem of coherent beam combining in multi-aperture arrays with large pointing errors, a control strategy based on the light intensity gradient trap is proposed. This method preprocesses the detected light intensity information from the target region before it enters the photodetector. The light intensity gradient trap filters the light intensity between the pointing errors of the spots in the extended area and the light intensity data. Through simulation, pointing error correction of six incoherent and coherent beams is successfully achieved using a stochastic parallel gradient descent algorithm. To further verify the feasibility of the method, a coherent beam combining system is constructed, with an adaptive fiber-optics collimator array used for the pointing error correction and a silicon-based optical chip used for piston aberration correction. Through piecewise control, a coherent beam combining of six beams containing pointing errors is achieved. The feasibility of pointing error correction based on the light intensity trap is verified theoretically and experimentally. This research is expected to provide new ideas and technical support for the development of the phased fiber laser array.