Abstract

Directly-modulated laser (DML) is widely employed in intensity modulation and direct detection (IMDD) system due to its low cost and high output power. However, the corresponding frequency chirp is regarded as one of the main disadvantages for its application in passive optical networks (PONs). In this paper, we theoretically analyze the frequency response evolution of DML based system under different chirp and dispersion conditions, proving that the system bandwidth can be improved by interactions between negative dispersion and DML chirp. Based on this concept, we experimentally demonstrated downstream 50 Gb/s PAM4 signal transmission over 20 km single-mode fiber (SMF) access based on the 10 Gb/s DML operating at 1310 nm and avalanche photodiode (APD). A dispersion-shifted fiber (DSF) providing −150 ps/nm dispersion at 1310 nm in the optical line terminal (OLT) is used to pre-equalize the frequency response of bandwidth-limited directly modulated signals in the optical domain. Thanks to our proposed dispersion-supported equalization (DSE) technique, the system bandwidth can be improved by 5 GHz. Feed-forward equalization (FFE), decision feedback equalization (DFE) and Volterra filter are employed to evaluate the signal performance improvement, respectively. By evaluating the receiver sensitivity, the DSE combined with FFE scheme shows 2 dB improvement than the complex Volterra algorithm, indicating its potential to reduce the complexity of digital signal processing (DSP) and therefore a lower cost and power consumption in PON.

100-Gb/s TWDM-PON based on 10G optical devices

Zhengxuan Li, Lilin Yi, Honglin Ji, and Weisheng Hu
Opt. Express 24(12) 12941-12948 (2016)

Intensity directed equalizer for the mitigation of DML chirp induced distortion in dispersion-unmanaged C-band PAM transmission

Kuo Zhang, Qunbi Zhuge, Haiyun Xin, Mohamed Morsy-Osman, Eslam El-Fiky, Lilin Yi, Weisheng Hu, and David V. Plant
Opt. Express 25(23) 28123-28135 (2017)

28 Gb/s duobinary signal transmission over 40 km based on 10 GHz DML and PIN for 100 Gb/s PON

Zhengxuan Li, Lilin Yi, Xiaodong Wang, and Weisheng Hu
Opt. Express 23(16) 20249-20256 (2015)

Using adaptive four-band OFDM modulation with 40 Gb/s downstream and 10 Gb/s upstream signals for next generation long-reach PON

C. H. Yeh, C. W. Chow, H. Y. Chen, and B. W. Chen
Opt. Express 19(27) 26150-26160 (2011)

Symmetric 10 Gbit/s 40-km reach DSP-based TDM-PON with a power budget over 50 dB

Takuya Kanai, Masamichi Fujiwara, Ryo Igarashi, Noriko Iiyama, Ryo Koma, Jun-ichi Kani, and Tomoaki Yoshida
Opt. Express 29(11) 17499-17509 (2021)