Abstract Nanophotonic devices with high densities are extremely attractive because they can potentially merge photonics and electronics at the nanoscale. However, traditional integrated photonic circuits are designed primarily by manually selecting parameters or employing semi-analytical models. Limited by the small parameter search space, the designed nanophotonic devices generally have a single function, and the footprints reach hundreds of microns. Recently, novel ultra-compact nanophotonic devices with digital structures were proposed. By applying inverse design algorithms, which can search the full parameter space, the proposed devices show extremely compact footprints of a few microns. The results from many groups imply that digital nanophotonics can achieve not only ultra-compact single-function devices but also miniaturized multi-function devices and complex functions such as artificial intelligence operations at the nanoscale. Furthermore, to balance the performance and fabrication tolerances of such devices, researchers have developed various solutions, such as adding regularization constraints to digital structures. We believe that with the rapid development of inverse design algorithms and continuous improvements to the nanofabrication process, digital nanophotonics will play a key role in promoting the performance of nanophotonic integration. In this review, we uncover the exciting developments and challenges in this field, analyse and explore potential solutions to these challenges and provide comments on future directions in this field.

中文翻译：

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数字纳米光子学：通往亚波长光子学集成的高速公路

摘要 具有高密度的纳米光子器件极具吸引力，因为它们有可能在纳米尺度上融合光子学和电子学。然而，传统的集成光子电路主要是通过手动选择参数或采用半解析模型来设计的。受限于小参数搜索空间，所设计的纳米光子器件一般功能单一，足迹可达数百微米。最近，提出了具有数字结构的新型超紧凑纳米光子器件。通过应用可以搜索完整参数空间的逆向设计算法，所提出的设备显示出几微米的极其紧凑的足迹。许多研究小组的研究结果表明，数字纳米光子学不仅可以实现超紧凑的单功能器件，还可以实现纳米级的微型化多功能器件和人工智能运算等复杂功能。此外，为了平衡此类设备的性能和制造公差，研究人员开发了各种解决方案，例如向数字结构添加正则化约束。我们相信，随着逆向设计算法的快速发展和纳米制造工艺的不断改进，数字纳米光子学将在提升纳米光子集成性能方面发挥关键作用。在这篇评论中，我们揭示了该领域令人兴奋的发展和挑战，