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تقليل التاثيرات اللاخطية في منظومات التقسيم المتعدد للطول الموجي العالية الكثافة == Mitigation of Fiber Nonlinearity Effects In Ultra High - Dence WDM System
Author name:
سيف حسام عبد الواحد
Supervisor name:
علي يوسف فتاح
General topic:
Electrical, Electronic and Communications Engineering
Specific topic:
Communications Engineering
Degree:
Master
University:
University of Technology - Electrical Engineering Department - Electronic Engineering Branch
Language:
English
University location:
Baghdad
First pages:
34T481 - p.pdf
Abstract:
The optical signal is severely degraded when transmitted in the fiber due to both the linear and nonlinear distortions. It is well known that, the linear distortions in single mode fiber include chromatic dispersion (CD) and polarization - mode dispersion (PMD) while self - phase modulation (SPM), cross phase modulation (XPM) and four - wave mixing (FWM) are considered the most among nonlinear distortions. To deal with the nonlinear impairments, a number of techniques, such as electronic equalization, pre - coding, digital back - propagation(BP), pre - chirping, optical phase conjugation (OPC) and nonlinearity management, are developed and improved. In the present work, a method called Fractional Fourier Transform (FRFT) has been applied to mitigate fiber nonlinearity impairments. The Fractional Fourier Transform is a time - frequency distribution and an extension of the classical Fourier transform. Time domain FRFT can be implemented by using time lens according to the optical time - space duality theory. The modulated optical pulses will be pre - distorted by an FRFT module before being launched into fiber links. In this work, 10 Gb/s optical fiber system with five spans, each of length 60 Km, for three types of modulation formats (Return - to - Zero Differential Phase Shift Keying (RZ - DPSK), Return - to - Zero Differential Quaternary Phase Shift Keying (RZ - DQPSK) and Carrier - Suppressed Return - to - Zero (CSRZ)), single and multi - channel transmission systems are designed and simulated using “OptiSystem (2011) version 10.0” software package. In order to analyze the transmission performance of the simulated systems without and with FRFT, a set of eye diagrams, optical spectrum visualizers, Q - factor versus input power and Bite Error Rate (BER) versus Signal to Noise Ratio (SNR) curves are presented to evaluate the influence of FRFTon the system performance. For CSRZ modulation format the Q - factor for single channel system at 0 dBm (input power) was 43.5 without FRFT and 78 with FRFT. The BER of sixteen channel system (channel No.8) at bit rate 10 Gb/s per channel, 300 Km link length of CSRZ modulation format with channel spacing of 50 GHz at SNR 10 dB without FRFT is 10 - 4.8 and 10 - 7.4 with FRFT. The BER of thirty two channel system (channel No.16) at bit rate 10 Gb/s per channel, 300 Km link length of CSRZ modulation format with channel spacing of 50 GHz at SNR 10 dB without FRFT is 10 - 4.6 and 10 - 6.4 with FRFT. The BER of thirty two channel system (channel No.16) at bit rate 10 Gb/s per channel, 300 Km link length of CSRZ modulation format with channel spacing of 25 GHz at SNR 10 dB without FRFT is 10 - 2.56 and 10 - 3.24 with FRFT.
