Integrated metamaterials are redefining the capabilities of silicon photonic chips. In providing lithographic control over dielectric permittivity, dispersion and anisotropy, they are enabling photonic devices with unprecedented performance. However, the implementation of these materials at telecom wavelengths often requires a fabrication resolution of the order of 100 nm and below, pushing current wafer-scale fabrication technology to its limits and hindering the widespread exploitation of on-chip metamaterials. Herein, a subwavelength grating metamaterial with bricked topology is proposed, that provides lithographic control over the metamaterial dispersion and anisotropy using a single etch Manhattan-like geometry with pixel dimensions up to 150 × 150 nm², thereby easing the path toward fabrication at wafer-scale. The behavior of these structures as biaxial crystals is analytically shown, validating their use in high performance on-chip beam-splitters. Through engineering of the metamaterial anisotropy tensor, the splitters are shown to exhibit sub-decibel insertion losses and imbalance over a 400 nm design bandwidth, via 3D FDTD simulations. The excellent device performance is demonstrated over a 140 nm bandwidth, limited by the measurement setup.

中文翻译：

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砖砌亚波长光栅：可定制的片上超材料拓扑

集成超材料正在重新定义硅光子芯片的能力。在提供对介电常数、色散和各向异性的光刻控制时，它们使光子器件具有前所未有的性能。然而，在电信波长下实施这些材料通常需要 100 nm 及以下数量级的制造分辨率，这将当前的晶圆级制造技术推向了极限，并阻碍了片上超材料的广泛开发。在此，提出了一种具有砖砌拓扑结构的亚波长光栅超材料，它使用像素尺寸高达 150 × 150 nm ²的单次蚀刻曼哈顿式几何结构对超材料色散和各向异性进行光刻控制，从而简化了晶圆级制造的道路。分析显示了这些结构作为双轴晶体的行为，验证了它们在高性能片上分束器中的使用。通过超材料各向异性张量的工程设计，通过 3D FDTD 模拟，分光器在 400 nm 设计带宽内表现出亚分贝的插入损耗和不平衡。在 140 nm 带宽上证明了出色的设备性能，受测量设置的限制。