Ultra-compact multifunctional integrated photonic modules have great practical significance to photonic integrated circuits (PICs). However, the design effect and efficiency of the existing mainstream inverse design algorithms are incompetent when designing these modules. We analyze their shortcomings in this task, and propose a new, to our knowledge, inverse design algorithm named polygon search (PS) algorithm to address these problems. We utilize the PS algorithm to design an integrated dual-channel mode-conversion-crossing waveguide module. This module integrates three functions: interconversion between TE0 and TE1, interconversion between TE0 and TE2, and channel crossing within only a 4 μm×4 μm footprint, and its performance is verified by experimental testing. It not only greatly reduces the total footprint of many PICs but also greatly improves their fabricating robustness. Furthermore, we propose a PS-designed mode mixer and a PS-designed bending waveguide, and connect them with the integrated modules to form a four-channel crossing-mode-division-multiplexing system. This system can provide multiple modes on the basis of channel crossing and transmit the output signal in the same direction in parallel within a single output waveguide, which significantly increases the communication bandwidth and decreases the footprint of PICs. At last, we demonstrate the effect and efficiency advantages of the PS algorithm over several mainstream inverse design algorithms by a comprehensive contrast experiment and explain these advantages in theory from several perspectives.

中文翻译：

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用于超紧凑多功能集成光子学设计的多边形搜索算法


超紧凑多功能集成光子模块对光子集成电路（PIC）具有重要的现实意义。然而，现有主流逆向设计算法在设计这些模块时，设计效果和效率都不够。我们分析了它们在这项任务中的缺点，并据我们所知提出了一种新的逆向设计算法，称为多边形搜索（PS）算法来解决这些问题。我们利用PS算法设计了集成双通道模式转换交叉波导模块。该模块集成了三个功能： TE 0和TE 1 , 之间的相互转换TE 0和TE 2 ，并且通道交叉仅在 4微米×4微米足迹，其性能通过实验测试得到验证。它不仅大大减少了许多 PIC 的总占地面积，而且还大大提高了它们的制造稳健性。此外，我们提出了PS设计的模式混频器和PS设计的弯曲波导，并将它们与集成模块连接起来形成四通道交叉模分复用系统。该系统可以在通道交叉的基础上提供多种模式，并在单个输出波导内沿同一方向并行传输输出信号，这显着增加了通信带宽并减少了PIC的占地面积。最后，我们通过全面的对比实验展示了PS算法相对于几种主流逆设计算法的效果和效率优势，并从多个角度从理论上解释了这些优势。