K. Y. Yang, J. Skarda, A. Dutt, G. H. Ahn, M. Sawaby, D. Vercruysse, A. Arbabian, S. Fan, J. Vučković, M. Cotrufo, and A. Alù, “Nonreciprocal Devices in Silicon Photonics,” Optics and Photonics News, Special Issue Year in Optics 2020, Vol. 31, No. 12, p. 38, (2020).