18,090-km 2-core Fiber Transmission Using Circulatory Directional Fan-in/Fan-out Devices. - Daiki Soma; Shohei Beppu; Lídia Galdino; Michael Lorenz; Qiulin Ma; Katsuhiro Iwasaki; Seiya Sumita; Kosuke Komatsu; Daniel J. Elson; Tomoaki Kiriyama; Katsuya Kito; Keito Kitamura; et al. (OFC, 2024)