A scheme that utilizes the 4-level pulse-amplitude-modulated (4PAM) signal as the re-modulated signal of colorless optical network units (ONUs) based on reflection semiconductor optical amplifiers (RSOAs) is proposed. The system with 10-Gb/s non-return-to-zero (NRZ) downstream and 5-Gb/s 4PAM upstream signals is theoretically analyzed and experimentally verified. Simulation and experimental results reveal that the 4PAM re-modulated signal yields better performance than the NRZ signal in the upstream. A receiver power penalty of 1.6 dB is also improved by the 4PAM signal at back-to-back (BtB) transmission, whereas another receiver power penalty of 1.5 dB improved after 30-km single mode fiber transmission, where 4PAM signals are used as upstream signal.
© 2012 Chinese Optics Letters
(060.2330) Fiber optics and optical communications : Fiber optics communications
(060.1155) Fiber optics and optical communications : All-optical networks
(230.4480) Optical devices : Optical amplifiers
Fiber Optics and Optical Communications
Yueying Zhan, Min Zhang, Lei Liu, Mingtao Liu, Zhuo Liu, and Xue Chen, "Experimental and theoretical analyses of RSOA-based colorless-ONUs with 4PAM signal in the up-link," Chin. Opt. Lett. 10, 090602-090602 (2012)