@article {Tsakmakidis20201097,
	title = {Nonreciprocal cavities and the time-bandwidth limit: comment},
	journal = {Optica},
	volume = {7},
	number = {9},
	year = {2020},
	note = {cited By 3},
	pages = {1097-1101},
	abstract = {In their paper in Optica 6, 104 (2019), 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{\textquoteright}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. {\textcopyright} 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement},
	doi = {10.1364/OPTICA.384840},
	url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090897547\&doi=10.1364\%2fOPTICA.384840\&partnerID=40\&md5=d814be76f5f6ddbc5987440db6d4f94c},
	author = {K. L. Tsakmakidis and You, Y. and Stefa{\'n}ski, T. and Shen, L.}
}
