利用光纤阵列传输高功率光能,并针对基模高斯光,提出了一种通用的满足达曼光栅分束耦合约束条件的参数设计方法。首先,确定了系统组成元件并建立数学模型。然后,利用MATLAB软件仿真1×6达曼光栅分束,得到的子光斑束腰半径为20.31 μm、两两间距为127.7 μm,其总衍射效率为84.50%、不均匀度为0.23%。由光栅衍射理论与远场发散角分别计算出子光斑半径,对比仿真结果可知,对于基模高斯光入射,由平面波推导出的子光斑半径公式不适用,子光斑半径与入射光半径成反比,而光栅周期数对其无影响,并通过了实验验证。为了满足耦合约束条件,提出了一种通用的系统参数设计方法,通过改变波长、束腰半径、准直倍率、光栅周期长度与聚焦透镜焦距等参数,得到了精确耦合所需的子光斑半径与间距。

To transmit high power optical energy through optical fiber array and aiming at fundamental-mode Gaussian light, a general parameter design method to satisfy the Dammann grating constraint conditions of beam splitting coupling is proposed. First, the components of the system are determined and their mathematical models are given. Then, 1×6 Dammann grating beam splitting is simulated by MATLAB, obtaining sub-spots with beam waist radius of 20.31 μm and distance of pairwise spacing is 127.7 μm, with a total diffraction efficiency of 84.50%, and an inhomogeneity of 0.23%. According to the optical grating diffraction theory and laser divergence angle, the sub-spots radius is calculated. Comparing the simulation results, for incident fundamental-mode Gaussian beam, the sub-spots radius formula derived from plane wave is not applicable. The radius of the sub-spots is inversely proportional to the radius of the incident light and the number of grating periods has no effect on it. And it is proved by experimental result. In order to satisfy the coupling constraint condition, a general system parameter design method is presented, which adjusts the spot radius, waist radius, collimation ratio, grating unit period length, and focal length of the focusing lens, the spot radius and spacing required by precise coupling are obtained.