Analysis of chromatic dispersion compensation and carrier phase recovery in long-haul optical transmission system influenced by equalization enhanced phase noise

Abstract

The performance of long-haul coherent optical fiber transmission system is significantly affected by the equalization enhanced phase noise (EEPN), due to the interaction between the electronic dispersion compensation (EDC) and the laser phase noise. In this paper, we present a comprehensive study on different chromatic dispersion (CD) compensation and carrier phase recovery (CPR) approaches, in the n-level phase shift keying (n-PSK) and the n-level quadrature amplitude modulation (n-QAM) coherent optical transmission systems, considering the impacts of EEPN. Four CD compensation methods are considered: the time-domain equalization (TDE), the frequency-domain equalization (FDE), the least mean square (LMS) adaptive equalization are applied for EDC, and the dispersion compensating fiber (DCF) is employed for optical dispersion compensation (ODC). Meanwhile, three carrier phase recovery methods are also involved: a one-tap normalized least mean square (NLMS) algorithm, a block-wise average (BWA) algorithm, and a Viterbi-Viterbi (VV) algorithm. Numerical simulations have been carried out in a 28-Gbaud dual-polarization quadrature phase shift keying (DP-QPSK) coherent transmission system, and the results indicate that the origin of EEPN depends on the choice of chromatic dispersion compensation methods, and the effects of EEPN also behave moderately different in accordance to different carrier phase recovery scenarios.

Analysis and Compensation of Chromatic Dispersion in Long-hauls Optical Coherent System

“…The zero-padded sequence is converted into the frequency domain by Fast-Fourier-Transform (FFT) [26,27]. Then, the resulting signal is multiplied by the inverse transfer function of the dispersive channel and finally transformed back to the time domain by an Inverse Fast Fourier Transform (IFFT) [18]:…”

“…In 2017, Xu et al [18] investigated a different Chromatic Dispersion compensation for 28-Gbaud dual-polarization QPSK over 2000 km Single Mode Fiber (SMF). The DCF is applied as optical compensation.…”

Comparative Study on Noise Reduction Effect of Fiber Optic Hydrophone Based on LMS and NLMS Algorithm

“…It is necessary to change the step size parameter µ to reduce the value of the steady-state error. Based on the LMS algorithm, the NLMS algorithm "normalizes" the fixed step size parameters by the energy of the input signal x(n), and continuously changes the step size parameter [15]. Therefore, the NLMS algorithm has higher adaptability, flexibility, and stability than the LMS algorithm.…”

Nonlinear Coherent Optical Systems in the Presence of Equalization Enhanced Phase Noise

“…The impact of EEPN usually scales with the fiber dispersion, the linewidth of the local oscillator (LO) or the transmitter (Tx) laser, the modulation format and the signal symbol rate [4], [5]. As it has been studied in [6]- [8], EEPN may significantly degrade the performance of optical fiber transmission systems. However, to the best of our knowledge, studies on EEPN so far have been only performed for the systems without considering any nonlinear interference (NLI).…”