论文标题
基于元图的自由空间多端口梁拆分器具有任意功率比率
Metasurface-Based Free-Space Multi-port Beam Splitter with Arbitrary Power Ratio
论文作者
论文摘要
光束分离器（BS）是光学系统中最关键的构建块之一。尽管扁平型BSS进行了各种尝试以使传统的立方体BS微型化，但要实现具有多端口输出，不均匀拆分率的超薄光学BS和可启用的外向方向，这仍然是一个挑战。本文中，我们基于独立于极化的全dielectric metasurface展示了一个自由空间光学多端口束分离器（MPB）。通过将优化的相模式通过基于梯度的迭代算法应用于无定形硅（A-SI）元信息，我们已经准备了各种具有任意预定预定的输出端口编号（2〜7）的MPBS样品（2〜7），功率比和输出光束的空间分布。实验结果表明，制造的MPBS可以在100 nm（1500〜1600 nm）的带宽内实现高总拆分效率（TSE，高于74.7％）和梁拆分忠诚度（相似性，高于78.4％）。我们设想这样的MPB可以为光学集成系统和各种应用提供出色的灵活性。
A beam splitter (BS) is one of the most critical building blocks in optical systems. Despite various attempts of flat-type BSs to miniaturize the conventional cube BS reported, it remains a challenge to realize an ultrathin optical BS with multi-port output, non-uniform splitting ratio and steerable outgoing directions. Herein, we have demonstrated a free-space optical multi-port beam splitter (MPBS) based on a polarization-independent all-dielectric metasurface. By applying an optimized phase-pattern paradigm via a gradient-descent-based iterative algorithm to amorphous silicon (a-Si) metasurfaces, we have prepared a variety of MPBS samples with arbitrarily predetermined output port number (2~7), power ratio and spatial distribution of output beams. The experimental results reveal that the fabricated MPBSs could achieve high total splitting efficiency (TSE, above 74.7%) and beam-splitting fidelity (similarity, above 78.4%) within the bandwidth of 100 nm (1500~1600 nm). We envision that such MPBS could provide fabulous flexibility for optical integrated system and diverse applications.
