Numerical simulations have become an essential design tool in the field of photonics, especially for nanophotonics. In particular, 3D finite-difference-time-domain (FDTD) simulations are popular for their powerful design capabilities. Increasingly, researchers are developing or using inverse design tools to improve device footprints and performance. These tools often make use of 3D FDTD simulations and the adjoint optimization method. We implement a commercial inverse design tool with these features for several plasmonic devices that push the boundaries of the tool. We design a logic gate with complex design requirements as well as a y-splitter and waveguide crossing. With minimal code changes, we implement a design that incorporates phase-encoded inputs in a dielectric-loaded surface plasmon polariton waveguide. The complexity of the requirements in conjunction with limitations in the inverse design tool force us to make concessions regarding the density of encoding and to use on–off keying to encode the outputs. We compare the performance of the inverse-designed devices to conventionally designed devices with the same operational behavior. Finally, we discuss the limitations of the inverse design tools for realizing complex device designs and comment on what is possible at present and where improvements can be made.

中文翻译：

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为紧凑型、相位编码、等离子体数字逻辑器件实施商业逆向设计工具

数值模拟已成为光子学领域必不可少的设计工具，尤其是对于纳米光子学。特别是，3D 时域有限差分 (FDTD) 仿真因其强大的设计能力而广受欢迎。越来越多的研究人员正在开发或使用逆向设计工具来改善设备占用空间和性能。这些工具通常使用 3D FDTD 模拟和伴随优化方法。我们为几个突破工具边界的等离子体设备实现了具有这些功能的商业逆向设计工具。我们设计了一个具有复杂设计要求的逻辑门以及一个 y 分离器和波导交叉。通过最少的代码更改，我们实现了一种设计，将相位编码输入纳入介电负载表面等离子体激元波导中。要求的复杂性以及逆向设计工具的局限性迫使我们在编码密度方面做出让步，并使用开关键控对输出进行编码。我们将逆向设计设备的性能与具有相同操作行为的常规设计设备进行比较。最后，我们讨论了逆向设计工具在实现复杂设备设计方面的局限性，并评论了目前的可能性和可以改进的地方。