4λ x 226 Gbps PAM4 Transmission Over 2-km SSMF with Differential Drive EA-DFB Lasers Under 1.5-Vppd Low Swing Voltage. - Ryosuke Hatai; Takanori Suzuki; Hideaki Matsuzaki; Masato Ito; Hiroshi Hamada; Syunya Yamauchi; Atsushi Mimura; Yuma Endo; Ryo Nakao; Hisashi Yoshida; Hyota Fujishima; Atsushi Tada; et al. (OFC, 2026)