提高主瓣的能量集中度和抑制栅瓣问题是当前光纤激光相控阵技术面向应用的关键。文中从说明激光相控阵在技术上难以满足λ/2的阵元间隔, 由此导致诸多栅瓣产生的原因入手, 并考虑到目前常用不等间隔栅瓣抑制方法将导致相控阵口径增大的难题, 提出了一种将遗传算法引入到光纤激光相控阵阵元分布优化的设想。主要方法是从最大限度抑制栅瓣的角度提出一个与主瓣能量集中度和主瓣/旁瓣对比度相关的适应度函数; 将遗传算法中的特征参数与光纤激光相控阵的主要参数相对应; 然后以20路阵元/阵元间隔为3倍波长、50路阵元/阵元间隔为20倍波长两种线阵情况为例,分别仿真计算了传统的等间距阵元和不等间距阵元分布, 及遗传算法优化阵元分布三种情况, 得到的光纤激光相控阵远场能量分布、主瓣能量集中度和主瓣与最大栅瓣对比度, 并对其进行了比较。结果表明, 遗传算法较等间距、不等间距方法的主瓣能量集中度分别提高了9.69%、3.33%, 主瓣与第一栅瓣能量对比度分别提高了13.12%、9%。由此可预期基于遗传算法优化的相控阵有望在同等激光发射总功率下获得更远的作用距离。

Improving the energy concentration of the main lobe and suppressing the grating lobe are the key to the application of optical fiber laser phased array technology. In this paper, the cutting point was the reason why laser phased array was difficult to satisfy the element spacing of λ/2 and then many grating lobes were produced. Considering the problem that the aperture of the phased array was enlarged by the method of suppressing the unequal-spacing grating lobe, a new idea of introducing genetic algorithm into the optimization of element distribution of optical fiber laser phased array was proposed. The main method was to propose a fitness function related to the main lobe energy concentration and the main lobe/side lobe contrast from the perspective of the maximum suppression of the lobe. The characteristic parameters of genetic algorithm were corresponded to the main parameters of fiber laser phased array. Then, taking two kinds of linear arrays as an example 20 line array element/array element interval as 3 times wavelength and 50 line array element/array element interval as 20 times wavelength, the traditional equally spaced array elements and unequal spacing, the array element distribution and the genetic algorithm optimized the array element distribution were simulated respectively. The distribution of the far-field energy, the main lobe energy concentration and the contrast between the main lobe and the maximum lobe of the fiber laser phased array were calculated and compared. The results show that the energy concentration of the main lobe is increased by 9.69% and 3.33% respectively, and the energy contrast between the main lobe and the first grating lobe is increased by 13.12% and 9% respectively. It can be seen that the phased array optimized based on genetic algorithm is expected to obtain a longer working distance under the same total power of laser emission.