In 2021, as optical technologies continue to demonstrate their advantages in telecom and data-center networks, we are also witnessing the attractive and promising progress on free-space optical communications and new technologies for fiber optic communications. Therefore, in this last issue of the Optical Communications and Networks Series in 2021, we have selected three contributions that address the (i) intelligent reflecting surface-assisted free-space optical communications, (ii) routing techniques for elastic optical networks with space division multiplexing, and (iii) non-orthogonal frequency-division multiplexing in optical networks.

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系列社论：光通信与网络

2021年，随着光技术在电信和数据中心网络中的优势不断显现，我们也见证了自由空间光通信和光纤通信新技术取得的令人瞩目的进展。因此，在 2021 年光通信和网络系列的最后一期中，我们选择了三篇文章，这些文章涉及 (i) 智能反射面辅助自由空间光通信，(ii) 空分弹性光网络的路由技术复用，以及 (iii) 光网络中的非正交频分复用。