Abstract
We propose a novel, to the best of our knowledge, cascade recurrent neural network (RNN)-based nonlinear equalizer for a pulse amplitude modulation (PAM)4 short-reach direct detection system. A 100 Gb/s PAM4 link is experimentally demonstrated over 15 km standard single-mode fiber (SSMF), using a 16 GHz directly modulated laser (DML) in C-band. The link suffers from strong nonlinear impairments which is mainly induced by the mixture of linear channel effects with square-law detection, the DML frequency chirp, and the device nonlinearity. Experimental results show that the proposed cascade RNN-based equalizer outperforms other feedforward or non-cascade neural network (NN)-based equalizers owing to both its cascade and recurrent structure, showing the great potential to effectively tackle the nonlinear signal distortion. With the aid of a cascade RNN-based equalizer, a bit-error rate (BER) lower than the 7% hard-decision forward error correction (FEC) threshold can be achieved when the receiver power is larger than 5 dBm. Compared with traditional non-cascade NN-based equalizers, the training time could also be reduced by half with the help of the cascade structure.
© 2020 Optical Society of America
Full Article | PDF ArticleMore Like This
Zhaopeng Xu, Chuanbowen Sun, Tonghui Ji, Jonathan H. Manton, and William Shieh
Opt. Express 27(25) 36953-36964 (2019)
Xiaoke Ruan, Fan Yang, Lei Zhang, Hao Ming, Yanping Li, and Fan Zhang
Opt. Lett. 45(19) 5344-5347 (2020)
Zheng Yang, Fan Gao, Songnian Fu, Xiang Li, Lei Deng, Zhixue He, Ming Tang, and Deming Liu
Opt. Lett. 43(15) 3542-3545 (2018)