In their paper in Optica 6, 104 (2019) [CrossRef] , Mann et al. claim that linear, time-invariant nonreciprocal structures cannot overcome the time-bandwidth limit and do not exhibit an advantage over their reciprocal counterparts, specifically with regard to their time-bandwidth performance. In this Comment, we argue that these conclusions are unfounded. On the basis of both rigorous full-wave simulations and insightful physical justifications, we explain that the temporal coupled-mode theory, on which Mann et al. base their main conclusions, is not suited for the study of nonreciprocal trapped states, and instead direct numerical solutions of Maxwell’s equations are required. Based on such an analysis, we show that a nonreciprocal terminated waveguide, resulting in a trapped state, clearly outperforms its reciprocal counterpart; i.e., both the extraordinary time-bandwidth performance and the large field enhancements observed in such modes are a direct consequence of nonreciprocity.

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不可逆的腔和时间带宽限制：评论

在它们中。光学纸6，104（2019）[交叉引用] ，曼等人。声称线性，时不变的不可逆结构不能克服时间带宽的限制，并且在它们的可逆带宽性能方面，没有表现出优于其可逆结构的优势。在本评论中，我们认为这些结论是没有根据的。在严格的全波模拟和深刻的物理论证的基础上，我们解释了时间耦合模式理论，Mann等人。根据他们的主要结论，不适合研究不可逆的俘获状态，而是需要麦克斯韦方程的直接数值解。基于这样的分析，我们表明，一个不可逆的端接波导导致陷波状态，明显优于其可逆的波导。也就是说，在这种模式下观察到的非凡的时间带宽性能和大的场增强都是不可逆的直接结果。