Iterative Fourier transform algorithm (IFTA) has been widely applied to achieve holograms in diffractive optical elements, however it is insufficient for designing holograms uploaded on liquid crystal on silicon (LCOS) to steer multi-beams in a wavelength selective switch (WSS). In this paper, a three-step hybrid algorithm including IFTA, Symmetrical IFTA with both phase and amplitude freedoms (SIFTA-2) and Genetic algorithm (GA) is developed to optimize the multi-casting hologram and experimentally demonstrated the multi-casting function of WSS. The reconstructed output field not only has max 128 fan-out patterns with flexible power ratio, but also can be adjusted to balance multi-indicators like reconstructed root mean square error (RMSE), diffraction efficiency and crosstalk power by setting flexible weightings of fitness functions in GA.

中文翻译：

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基于LCOS的波长选择开关多光束控制的混合算法

迭代傅里叶变换算法 (IFTA) 已被广泛应用于在衍射光学元件中实现全息图，但它不足以设计上传到硅基液晶 (LCOS) 上的全息图来控制波长选择开关 (WSS) 中的多光束。在本文中，开发了一种包括 IFTA、具有相位和幅度自由度的对称 IFTA (SIFTA-2) 和遗传算法 (GA) 的三步混合算法来优化多播全息图，并通过实验证明了多播功能WSS。重构输出场不仅具有最大128个扇出模式，具有灵活的功率比，而且可以通过设置灵活的适应度函数权重来调整以平衡重构均方根误差（RMSE）、衍射效率和串扰功率等多个指标在 GA 中。