Last version 03.06-2024. NL Thesis Presentation.pptx

Last version 03.06-2024. NL Thesis Presentation.pptx

1. Analysis and Compensation of Nonlinear Impairments in Optical Fiber communication systems Presented by: BOUAFIA Fatma Batoul DJERADI Bilel 1 3rd juin, 2024 – El-oued Academic Master People’s Democratic Republic of Algeria Ministry of Higher Education and Scientific Research Hamma Lakhdar University El-Oued Telecommunications sector Supervised by: Dr  : HADJADJI Narimane

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3. 3 1. Introduction 2. Optical Fiber Transmission 3. Digital Backpropagation technique 4. Nonlinearity Compensation Simulation 5. Conclusion and future work Presentation plan

4. 4 1. Introduction 2. Optical Fiber Transmission 3. Digital Backpropagation technique 4. Nonlinearity Compensation Simulation 5 . Conclusion and future work Presentation plan

5. Introduction Capacity growth is “driven” by technology innovation multimode fiber (0.85µm ) single mode fiber (1.3 and 1.55 µm) Improved fibers Technological breakthroughs Current optical fiber input power limit DFB: Distributed Feedback EDFA: Erbium doped fiber amplifier WDM: Wavelength division multiplexing NL effect Shannon limit OA bandwidth limitation 1st generation: Improved Transmission fibers 2nd generation:1.55 µm DFB laser 3rd generation: Optical amplification 5th generation : Coherent detection 4th generation : WDM systems 6th generation: SDM systems Improved fibers Figure 1: The evolution of optical fiber communication systems 5

6. Main characteristics of optical communication systems Multiplexing techniques High order modulation formats Multi core/mode fibers Non-linearity compensation Raman amplification Forward error correction (FEC) The complexity of the material Energy consumption Figure 2 : Main characteristics of optical fiber communication systems 6

7. 7 1. Introduction 2. O ptical Fiber Transmission 3. Digital Backpropagation technique 4. Nonlinearity Compensation Simulation 5 . Conclusion and future work Presentation plan

8. L ightwave propagation Wave propagation equation – NLSE NLSE: The nonlinear Schrödinger equation 8 Maxwell equations   Figure 4: Electromagnetic wave structure. Figure 3: The propagation of light in the optical fiber. The nonlinear Kerr effect The Dispersion Fiber attenuation Optical fiber transmission: wave p ropagation

9. Industrial context Existing systems: 100-400 Gb/s modulated optical systems per channel, with a total capacity up to 32 Tb/s. Sufficient capacity today But won't be enough in the near fu tu re  Need to design higher capacity optical transmission systems for similar achievable distances. “capacity crunch” but Must mitigate 9

10. 10 1. Introduction 2. O ptical Fiber Transmission 3 . Digital Backpropagation technique 4. Nonlinearity Compensation Simulation 5 . Conclusion and future work Presentation plan

11. Phase shift of the signal according to its intensity . Limiting to high powers . Intra-channel effects : interactions within the same channel Cross-effects : interactions between two or more channels Kerr Effect Transmitter Receiver t  1  2 XPM, FWM t SPM t t Introduction How to Compensate? 25

12. Digital Backpropagation compensation technique 12 DBP is a channel inversion technique that aims to remove fiber effects by digitally emulating the propagation of the received signal through a fictitious fiber link . (a) (b) Figure 5 : (a) Forward propagation process through the fiber, (b) Digital backpropagation propagation through the virtual fiber.

13. The dispersive step is performed in the frequency domain by inverting the frequency response of a dispersive fiber. W hile the nonlinear step is performed in the time domain by applying an inverse nonlinear phase shift proportional to the total power in both polarizations. 13 Digital Backpropagation compensation technique Figure 6 : The schematic of Digital Backpropagation algorithm for dual-polarization system .

14. 14 1. Introduction 2. O ptical Fiber Transmission 3. Digital Backpropagation technique 4 . Nonlinearity Compensation Simulation 5. Conclusion and future work Presentation plan

15. Mitigation of Self Phase Modulation effect in Long-Haul Dual Polarization Coherent Optical System 15

16. 16 System Model Figure 7 : PDM-QPSK Coherent Optical System configuration. Optical link SSMF PBC x

17. Simulation parameters Format PDM- 0.3RZ- QPSK R bit 56-112-224 Gbps R sym 14-28-56 Gbaud N bit 2 12 Samples / bit 64 Number of samples 262114 Wavelength (λ) 1550 nm N steps/span 4 17 Table 3.1: Set of system simulation parameters . Parameters SSMF Span length (L ) [km] 75 Attenuation (α ) [dB/km] 0.22 Dispersion (D ) [ps/ nm /km] 17 Dispersion slope (S ) [ps/ nm 2 /km] 0.08 Nonlinear refractive index (n 2 ) [ m 2 /W] 2.6× 10 −20 Nonlinear coefficient (γ) 1.31 Core effective area (A eff ) [ μm 2 ] 80 EDFA Gain 15 dB EDFA noise figure 5 dB Table 3.2: Transmission line parameters.

18. Simulation Results 18

19. Performance of nonlinear compensation Back to Back configuration The simulation is performed on 14-28-56 GBaud PDM-0.3RZ-QPSK system where the transmitter and receiver are directly connected without optical link. The btb performance serves as a reference for the overall system performance without any transmission impairments. 19 Figure 8 : The measured receiver sensitivity curve (BER versus OSNR) for three symbols rates.

20. Performance of nonlinear compensation Transmission configuration The simulation is performed on the single-channel 14-28-56 Gbps PDM-0.3RZ-QPSK system over uncompensated SSMF. 20 (a ) (b) Figure 9 : Q-factor versus optical signal-to-noise ratio for PDM-0.3RZ-QPSK System under different transmission scenarios, (a) 14 Gbaud, (b) 28 Gbaud, (c) 56 Gbaud

21. Performance of nonlinear compensation Transmission configuration The simulation is performed on the single-channel 14-28-56 Gbps PDM-0.3RZ-QPSK system over uncompensated SSMF. 21 (c) Figure 10: Q-factor versus optical signal-to-noise ratio for PDM-0.3RZ-QPSK System under different transmission scenarios, (a) 14 Gbaud, (b) 28 Gbaud, (c) 56 Gbaud . Configuration 14 Gbaud 28 Gbaud 56 Gbaud Btb transmission 12 dB 12.8 dB 13.3 dB w NLC compensation 12.8 dB 13 dB 14.5 dB w/o NLC compensation 14 dB 14.6 dB 16.5 dB

22. Performance of nonlinear compensation -Cont. 22 Figure 11 : BER versus OSNR for PDM-0.3RZ-QPSK System under different transmission scenarios, (a) 14 Gbaud, (b) 28 Gbaud, (c) 56 Gbaud . (a) (b) (c) Configuration 14 Gbaud 28 Gbaud 56 Gbaud Btb transmission Under FEC limit 12.3 dB 13 dB W NLC compensation 13 dB 13.8 dB w/o NLC compensation 12 dB 15.2 dB 16.6 dB

23. Performance of nonlinear compensation -Cont. Maximum reach The maximum attainable distance is evaluated when the performance of the system is still considerable after applying the nonlinear compensation. 23 Figure 12 : System reach as a function of the fiber launch power per channel for different values of symbol rate . The optimum power Maximum distance

24. Performance of nonlinear compensation -Cont. Maximum reach ( optimum step per span) We calculate the system performance per reach after applying the DBP algorithm. 2 steps for 14 GBaud 4 steps for 28 GBaud 8 steps for 56 GBaud 24 The optimum power Figure 13 : System reach as a function of the fiber launch power per channel for different symbol rates. Maximum distance

25. 25 1. Introduction 2. Chromatic Dispersion Compensation 3. Nonlinearity Compensation 4. Conclusion and future work Presentation plan

26. Conclusion and Future work 26 Nonlinearity compensation based digital backpropagation (DBP) has been performed for a 14-28-56 Gbaud single-channel PDM-0.3RZ-QPSK system. Intra-channel nonlinear interference (SPM) tolerance was improved by increasing the OSNR sensitivity with a bit error rate of 1.54×10^-4 and a Q factor of 10.25 dB. Therefore , after optimum DBP steps , the maximum ranges exceeded 5100 km, 4625 km, and 4275 km for 14, 28, and 56 Gbaud, respectively Extending the NLC implementation to other nonlinear effects compensation techniques, such as machine learning. Integrating with high-level modulation formats such as PDM-64 QAM and PDM-256 QAM.

27. 27 Thank you for your attention