Effect of random phase errors on coherent beam combining based on liquid crystal phased array

Abstract

The effect of random phase errors on coherent beam combining based on liquid crystal phased array is studied. Utilizing the Fraunhofer propagation principle and probability theory, the analytical expressions of the far-field intensity distribution functions of the output beam are derived. According to these expressions, it can be concluded that as the phase errors increase, the peak intensity of the combined beam in the far-field decreases, the main lobe width widens and the error of deflection angle becomes greater. Considering the influence of random phase errors on the three parameters, a threshold of phase control precision can be designated. When the phase errors are less than the threshold, the performance degradation of the CBC system caused by the phase errors can be accepted. The computer simulations illustrate that the conclusions obtained from analytical expressions are reasonable. In the simulation parameters, the threshold of the phase control precision is λ / 20. The results in this paper can be employed to research methods to reduce the adverse effects of random phase errors and can also be used to determine the phase control precision when using phase-locking algorithms to lock the phase of the beams to be combined in the CBC system.