Digital subcarrier multiplexing for fiber nonlinearity mitigation in coherent optical communication systems.

Meng Qiu,Mathieu Chagnon,Mohamed Morsy-Osman,Yuliang Gao,Qunbi Zhuge,David V Plant,Xian Xu

doi:10.1364/oe.22.018770

Abstract

In this work we experimentally investigate the improved intra-channel fiber nonlinearity tolerance of digital subcarrier multiplexed (SCM) signals in a single-channel coherent optical transmission system. The digital signal processing (DSP) for the generation and reception of the SCM signals is described. We show experimentally that the SCM signal with a nearly-optimum number of subcarriers can extend the maximum reach by 23% in a 24 GBaud DP-QPSK transmission with a BER threshold of 3.8 × 10(-3) and by 8% in a 24 GBaud DP-16-QAM transmission with a BER threshold of 2 × 10(-2). Moreover, we show by simulations that the improved performance of SCM signals is observed over a wide range of baud rates, further indicating the merits of SCM signals in baud-rate flexible agile transmissions and future high-speed optical transport systems.

Highlights

Digital signal processing (DSP) has been widely employed in coherent optical (CO) communication systems and enables effective compensation for many types of linear impairments such as chromatic dispersion (CD) and polarization mode dispersion (PMD)
In this work we experimentally investigate the improved intrachannel fiber nonlinearity tolerance of digital subcarrier multiplexed (SCM) signals in a single-channel coherent optical transmission system
We show experimentally that the SCM signal with a nearly-optimum number of subcarriers can extend the maximum reach by 23% in a 24 GBaud DP-QPSK transmission with a BER threshold of 3.8 × 10−3 and by 8% in a 24 GBaud DP-16-QAM transmission with a BER threshold of 2 × 10−2

Summary

Introduction

Digital signal processing (DSP) has been widely employed in coherent optical (CO) communication systems and enables effective compensation for many types of linear impairments such as chromatic dispersion (CD) and polarization mode dispersion (PMD). Pulse shaping was proposed in [8, 9] as an alternative to mitigate fiber nonlinearities by increasing the power of the high-frequency components in the signal spectra. The drawback of this method is the reduced spectral efficiency (SE) because an increased bandwidth is usually required for a noticeable performance improvement. In our previous work we have already demonstrated the feasibility of generating SCM signals using DACs and experimentally investigated the improved intra-channel nonlinearity tolerance of SCM signals in a 24-GBaud single-channel dual polarization (DP) quadrature phase shift keying (QPSK) transmission system [16].

Subcarrier multiplexing and de-multiplexing

Findings

Conclusion