Mitigation of Fiber Nonlinear Effects in 1.28 Tbps DQPSK Modulated DWDM System

Abstract

The main limitation factor of high capacity multichannel DWDM (Dense Wavelength Division Multiplexing) systems are fiber nonlinear effects. The optical signal is severely degraded due to fiber nonlinear effects also known as Kerr fiber nonlinearity. Nonlinear effects under investigation are self-phase modulation (SPM) and cross-phase modulation (XPM). There are several methods to compensate these nonlinear distorts, some less or more effective. Nonlinear distort due to SPM and XPM can be effectively mitigated through implementation of optical DQPSK modulation over commonly used intensity modulation known as OOK (On-Off Keying). This paper presents a numerical simulation model of 1.28 Tbps DWDM system with optical DQPSK modulation. We present several scenarios and methods to mitigate fiber nonlinear effects including Fractional Fourier Transform (FrFT). Linear and nonlinear effects are considered together, so we implement the inline FrFT module in the optical domain which causes a time-frequency plane rotation to mitigate combined linear and nonlinear effects. The performance of proposed 1.28 Tbps DQPSK modulated DWDM system is evaluated in term of bit error rate (BER) and Q factor value.