1. Doctoral oral defence McConnell Engineering Building, Room 603 April 11, 2016 Mathieu Chagnon Optical Communications for Long-Haul, Short-Reach, and Chip-Scale Distances Enabled by Digital Signal Processing

2. Outline Introduction  Motivation Coherent Long-haul  Polarization recovery algorithm  Constant power format Passive and Active Silicon Photonics  Passive: Four-wave mixing in Silicon Nanowire  Active: 1D Intensity modulator in SiPh Optical Short Reach  3D Modulation for Self-Beating Direct Detection Conclusion & Future work 2

3. Outline Introduction  Motivation Coherent Long-haul  Polarization recovery algorithm  Constant power format Passive and Active Silicon Photonics  Passive: Four-wave mixing in Silicon Nanowire  Active: 1D Intensity modulator in SiPh Optical Short Reach  3D Modulation for Self-Beating Direct Detection Conclusion & Future work 3

4. 4 Global growth of IP Traffic, by Devices: From 2014 to 2019 Motivation 60 72 88 109 135 168 Source: Cisco’s Visual Networking Index (VNI), Global IP Traffic Foreacast, 2014–2019 CAGR ≈ 64 % (!) Annual Global IP traffic (Fun facts): 5× over past 5 years 3× over next 5 years at a CAGR of 23% (2014-2019) # of devices connected to IP networks ≈ 3× the global population in 2019

5. Outline Introduction  Motivation Coherent Long-haul  Polarization recovery algorithm  Constant power format Passive and Active Silicon Photonics  Passive: Four-wave mixing in Silicon Nanowire  Active: 1D Intensity modulator in SiPh Optical Short Reach  3D Modulation for Self-Beating Direct Detection Conclusion & Future work 5

6. 6 Coherent Long-Haul Complex Optical Modem Optical Coherent Receiver ? Jones Stokes Rotation e.g.: DP-16QAM

7. 7 New Polarization Derotation Algorithm 1)Convert receiver Jones to Stokes 2)Power discriminating filter 3)Locate 3 distinct “clusters” 4)Fit a plane in a LMS sense passing through the clusters 5)Bring the plane back to where it is supposed to be Our Proposed Stokes-based Method Constant Modulus Algorithm (CMA) VS -with noise -with rotation -after power filter

8. 8 New Polarization Derotation Algorithm DP-QPSK

9. 9 DP-16QAM New Polarization Derotation Algorithm

10. 10 DP-64QAM New Polarization Derotation Algorithm

11. Outline Introduction  Motivation Coherent Long-haul  Polarization recovery algorithm  Constant power format Passive and Active Silicon Photonics  Passive: Four-wave mixing in Silicon Nanowire  Active: 1D Intensity modulator in SiPh Optical Short Reach  3D Modulation for Self-Beating Direct Detection Conclusion & Future work 11

12. 12 Constant Power Format Field Propagation inside Single Mode Fiber : Manakov-PMD : Total power Idea:Create a complex constellation that minimize the temporal power variation of ∀ k = {1, 2, 3, …., 32} Symbol S k s.t.

13. 13 Constant Power Format StokesJones 8PolSK-QPSK

14. 14 Constant Power Format 8PolSK-QPSK with noise DP-8QAM with noise VS Comparison of the formats

15. 15 Constant Power Format: Results

16. Outline Introduction  Motivation Coherent Long-haul  Polarization recovery algorithm  Constant power format Passive and Active Silicon Photonics  Passive: Four-wave mixing in Silicon Nanowire  Active: 1D Intensity modulator in SiPh Optical Short Reach  3D Modulation for Self-Beating Direct Detection Conclusion & Future work 16

17. Anomalous dispersion Flat disp. slope @ ~1550 nm 1-dB BW: 37 nm Four-wave mixing in Silicon Nanowire First high baud rate (22Gbaud), high order QAM (16) 1-to-6 WM in a 20 mm long passive SNW. Test Bed: Device : Some properties… 17

18. Four-wave mixing in Silicon Nanowire Results : Results demonstrate the capability of a silicon based approach to achieve all-optical multicast switching. Highlights the potential for future on-chip optical interconnection.

19. Outline Introduction  Motivation Coherent Long-haul  Polarization recovery algorithm  Constant power format Passive and Active Silicon Photonics  Passive: Four-wave mixing in Silicon Nanowire  Active: Intensity modulator in SiPh Optical Short Reach  3D Modulation for Self-Beating Direct Detection Conclusion & Future work 19

20. 20 112 Gb/s short reach Tx with SiPh IM First demonstration of : We will just present the following : The test bed / the SiPh Intensity Modulator Present some system performance results:  Q/BER versus bit rate  BER versus Distance 112 Gb/s 10 km of SMF fiber BER below threshold of 3.8×10 −3 In SiPh platform

21. 21 112 Gb/s short reach Tx with SiPh IM Setup to test the SiPh Intensity Modulator DAC ADC Test Bed …

22. 22 112 Gb/s short reach Tx with SiPh IM Better For a target bit rate, chose optimum PAM order Q-factorBER

23. 23 112 Gb/s short reach Tx with SiPh IM At λ=1310 nm, the 56 GBaud PAM4 signal is not affected by Chromatic Dispersion 112 Gb/s, vary distance, fixed Rx power 112 Gb/s, vary distance Reach limited by fiber attenuation 10 km @ BER < 3.8×10 −3

24. Outline Introduction  Motivation Coherent Long-haul  Polarization recovery algorithm  Constant power format Passive and Active Silicon Photonics  Passive: Four-wave mixing in Silicon Nanowire  Active: Intensity modulator in SiPh Optical Short Reach  3D Modulation for Self-Beating Direct Detection Conclusion & Future work 24

25. 25 3D Modulation for Self-Beating DD The format relies on 3 dimensional modulation of a lightwave : The intensity on polarization The phase between polarizations and Over 4 levels (2 bits) Over 4 levels (2 bits) First demonstration of : 350 Gbit/s transceiver Employing Direct Detection Novel format at 6 bits/symbol

26. 26 3D Modulation for Self-Beating DD In a nutshell …. We generate a 4D Power Vector at the Tx Power on Inter-Pol. phase : 1) 2) The fiber channel rotates this Power Vector = Transmitter architecture :

27. 3D Modulation for Self-Beating DD 4) We Real-Time sample the Vector 5) We apply DSP to recover the transmitted 4D Power Vector 3) We Direct Detect this rotated Power Vector via Self-beating of the signal

28. 28 Real-Time Samples … = Time 3D Modulation for Self-Beating DD Employing a 4-by-4-by-Time MIMO does simultaneously 1.Polarization derotation 2.Mitigation of residual Tx ISI 3.Mitigation of Rx-induced ISI The DSP is a Multiple-Input Multiple Output (MIMO) filter Received 4D Power Vector MIMO processing DSP filter Recovered Tx 4D Power Vector

29. 29 3D Modulation for Self-Beating DD Results …

30. Outline Introduction  Motivation Coherent Long-haul  Polarization recovery algorithm  Constant power format Passive and Active Silicon Photonics  Passive: Four-wave mixing in Silicon Nanowire  Active: Intensity modulator in SiPh Optical Short Reach  3D Modulation for Self-Beating Direct Detection Conclusion & Future work 30

31. 31 Summary of Original Contributions [1] Mathieu Chagnon, et al., Opt. Express, vol. 20, no. 25, pp. 27847-27865 (2012) [2] Mathieu Chagnon, et al., Opt. Express, vol. 21, no. 25, pp. 30204-30220 (2013) [3] Mathieu Chagnon, et al., IEEE Photon. Technol. Lett., vol. 27, no. 8, pp. 860-863 (2015) [4] Mathieu Chagnon, et al., Opt. Express, vol. 22, no. 17, pp. 21018-21036 (2014) [5] Mathieu Chagnon, et al., J. Lightw. Technol., vol. 33, no. 7, pp. 1380-1387 (2015) [6] Mathieu Chagnon, et al., J. Lightw. Technol., vol. 34, no. 1, pp. 188-195 (2016) [7] Mathieu Chagnon, et al., in Proc. of OFC 2015, Post Deadline Paper Th5B.2 (2015)

32. 32 Future Research Coherent Long-haul … Short Reach Data Center Interconnects … Compensation / Mitigation of nonlinear effects in single mode fibers  Digital back-propagation  Volterra series filtering  Perturbation-based nonlinear compensation  Novel modulation formats  Coding How to increase binary throughputs per wavelength while maintaining cost, size & power at levels that are commercially acceptable ? Integration of photonics with electronics … Silicon ? III-V ? Hybrid ?

33. 33 Forget about assembling individual pre-packaged components to form a greater system… Integrate all on chip! Final Word … Electronic-Photonic integrated circuits

34. Thank you ! …. Questions ?

35. Motivation Fun facts and forecasts using Cisco’s Visual Networking Index (VNI) 35 Annual Global IP traffic: End of 2016: will pass the zettabyte (10 21 bytes) 2019: will reach 2 zettabytes 5× over past 5 years 3× over next 5 years at a CAGR of 23% (2014-2019) Metro traffic ≈ 66% of total IP traffic by 2019 # of devices connected to IP networks ≈ 3× the global population in 2019

36. Capacity Needs in Intra- and Inter- Data Center Interconnects: Growth in Data Center Traffic Motivation 36 Source: Cisco Global Cloud Index: Forecast and Methodology, 2014-2019, Cisco Press, 2015 Cloud-based services already dominate DC traffic  Will increase with time Global DC traffic will grow nearly 3X by 2019 Global DC traffic will reach 10.4 zettabytes per year (2019) 83% of all DC traffic will come from the cloud Cloud DC traffic will grow at 33% CAGR (4.1-fold) from 2014 to 2019 3.4 4.4 5.6 7.0 8.6 10.4

37. 37 New Polarization Derotation Algorithm Experimental Validation : Test bed

38. 38 New Polarization Derotation Algorithm Experimental Validation : Test bed New : Multi Wavelength Transmission

39. 39 112 Gb/s short reach Tx with SiPh IM Q-Factor model for multilevel PAM formats μ2μ2 σ1σ1 σ2σ2 μ1μ1 I th Background: Q for 2-level (PAM2)

40. μ1μ1 σ2σ2 σ1σ1 μ2μ2 I th-1/2 μ3μ3 μ4μ4 σ4σ4 σ3σ3 I th-2/3 I th-3/4 112 Gb/s short reach Tx with SiPh IM Q-Factor model for multilevel PAM formats 40 BER for PAM-N : Q-factor for PAM-N : Improvement in accuracy of optimum threshold I th :

41. 112 Gb/s short reach Tx with SiPh IM 41 PAM2PAM4 PAM8 PAM16

42. 42 112 Gb/s short reach Tx with SiPh IM Study the impact on BER when varying the number of Tx and Rx equalizing taps … PAM4 112 Gb/sPAM8 112 Gb/s Rx Tx Rx Tx Different combinations of (Tx,Rx) taps count gives a target BER

43. 43 Coherent Long-Haul or SMF Inside, polarization varies

44. New Polarization Derotation Algorithm 44 DP-QPSKDP-16QAMDP-64QAM Stokes Jones

45. 45 New Polarization Derotation Algorithm Stokes Based Polarization Recovery Converting Jones vector to Stokes vector representation: Jones Stokes 2D Complex Valued 3D Real Valued

46. 46