PERFORMANCE IMPROVEMENT OF NONLINEARITY COMPENSATION USING OPTICAL PHASE CONJUGATION FOR METRO DWDM SYSTEMS WITH OPTICAL ADD DROP MULTIPLEXERS
Keywords:Optical Add-Drop Multiplexing, metro system, Optical phase conjugation, Nonlinear compensation, Wavelength Division Multiplexing
Wavelength Division Multiplexing (WDM) has been widely applied in optical adddrop multiplexing (OADM) fiber metro systems with an increasing number of wavelength channels and sufficiently narrow channel spacing. The problem that appears here is the signal distortion produced by dispersion and nonlinearity effects. To cope with these effects, many compensation solutions have been introduced, such as digital compensation (DC) solutions on technology of digital signal processing (DSP) or optical phase conjugation (OPC) on alloptical domain. In fact, research on using OPC to compensate for dispersion and nonlinearity in metro transmission systems are incomplete, especially with large number multiplexing systems. In this paper, we propose to use OPC for dispersion and nonlinear compensation in DWDM metro systems. Specifically, we focus on two common types of modulation signals: QPSK and 16-QAM; operations in 16- and 32-channel dense WDM system. The simulation results show that the system quality increases significantly when using OPC to compensate for dispersion and nonlinearity, e.g. when transmitting 16-QAM signals in a 32-channel system passing through 20 add/drop nodes, the gain of Q factor is greater than 2 dB.