Quaternion Approach to Solve Coupled Nonlinear Schr?dinger Equation and Crosstalk of Quarter-Phase-Shift-Key Signals in Polarization Multiplexing Systems
LIU Lan-Lan1, WU Chong-Qing1**, SHANG Chao2, WANG Jian1, GAO Kai-Qiang1
1Institute of Optical Information, and Key Lab of Education Ministry on Luminescence and Optical Information Technology, School of Science, Beijing Jiaotong University, Beijing 100044 2State Key Laboratory of Information Photonics and Optical Communication, School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876
Abstract：The quaternion approach to solve the coupled nonlinear Schr?dinger equations (CNSEs) in fibers is proposed, converting the CNSEs to a single variable equation by using a conception of eigen-quaternion of coupled quaternion. The crosstalk of quarter-phase-shift-key signals caused by fiber nonlinearity in polarization multiplexing systems with 100 Gbps bit-rate is investigated and simulated. The results demonstrate that the crosstalk is like a rotated ghosting of input constellation. For the 50 km conventional fiber link, when the total power is less than 4 mW, the crosstalk effect can be neglected; when the power is larger than 20 mW, the crosstalk is very obvious. In addition, the crosstalk can not be detected according to the output eye diagram and state of polarization in Poincaré sphere in the trunk fiber, making it difficult for the monitoring of optical trunk link.
2015, Vol. 32 
