Self Coherent Detection & Reflective Modulation for Optical Access Networks (FTTH )

1. Acknowledgement: Piano+ EU Multi-National Program: Project OTONES(8 academic + industrial partners in Israel, Germany & UK ) also funded by the Israeli Chief Scientist Office Self Coherent Detection &Reflective ModulationforOptical Access Networks (FTTH) Amos Agmon, Moshe Nazarathy Technion, Israel Institute of Technology Talk given at Optical Engineering 2014 Netanya, Israel

2. Outline • Motivation and system design guidelines • Introduction: Optical Detection and Motivation to Self-coherent detection • Reflective Modulation • Combining Down-Stream(DS) & Up-stream (US) • OTONES Network design • Conclusions 2

3. Power dissipation of Information and Communication Equipment* Access Network and Home Gateway: ~ 10 W/user Shared Network Equipment ~ 1 W/user Home Devices: ~ 100 W/user Customer Premises * Interview with P. Vetter, Bell Labs, Sep-2010, http://www.youtube.com/watch?v=-M-9v7OdtFY 3

4. Motivation & Design Guidelines • Access Networks required to increase data throughputs while reducing power dissipation • Designing an access-network (FTTH) allowing for low-complexity, power-efficient Optical Network Units (ONU=Customer Premises Equipment) • Laserless, colorless low complexity ONUs • Low rate signal processing • ≥1 Gbps ONU peak Down-Stream (DS) throughput • FSAN Class B+ ODN (29 dB loss budget per Optical Distribution Network (ODN)) • Split ratio ≥ 1:64 4

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6. Intro. : Optical Transmission doubling data throughput by means of simultaneous transmission of I & Q 6

7. Intro. : Optical Detection 7

8. Intro. : Optical Detection PD 8

9. Intro. : Optical Detection 9

10. Intro. : Limits of Direct Detection PD Undetectable I-Q Mixture 10

11. Solution: Coherent (heterodyne)Det. EXPENSIVE SOLUTION LO PD 11

12. Coherent Det. drawbacks • Complex and expensive: Tunable laser required • Prone to frequency drifts and Phase noise, highly stable lasers required for large constellations • Phase noise is enhanced by Equalization Currently, Coherent Det. is prohibitive for mass deployed communication links 12

13. Self Coherent Tx Tx LO mixed at Tx output: 13

14. Self Coherent Advantages • Reduced Rx complexity: Single Photo-Diode, Laserless, colorless • Tx Remains simple: Generating a locked pair is not hard • Phase noise immunity: Both for Laser PN & Non-linear Self Phase Modulation (SPM)! PN canceled out! 14

15. Self Coherent - Summary • Spectral efficiency of Coherent Detection • Allows for Linear equalization (CD, PMD mitigation) • Laser coherency (Linewidth) does not effect Rx performance→ Low quality laser may be used • Simple Tx & Rx 15

16. Up-Stream: Reflective Modulation forLaserless Optical Network Unit (ONU) 3 dB coupler ONU US Carrier source 16

17. Uni-directional Reflective Modulation Reflective Tx 17

18. Bi-directional Reflective Modulation Reflective Tx 18

19. Bi-directional Reflective Modulation Reflective Tx PUDG pattern Optical SSB 19

20. OTONES network • A new bi-directional access network designed from the ground up at the system, sub-system and component levels • low-cost • power-efficient • long-reach • spectral-efficiency • Applying Self-coherent det. & reflective modulation • 1 Gbps (peak) per user, low rate ADC (<500 MSamp/s) • Total Throughput: • Class I: 10G/10G over 12.5 GHz – 40 dB reach - lowest-cost • Class II: 20G/20G over 25 GHz – 38.5 dB reach - mid-cost • Class III: 40G/40G over 50 GHz – 35 dB reach - highest cost 20

21. 11 dB feeder fiber optical filtering +OA Plant architecture of OTONES long-reach PON: Class B+ ODNs: 29 dB Loss budget 11 dB feeder + 29 dB ODN =40 dB loss budget (Class I) Backward-compatible w/ existing ODN PON Plant and may even co-exist with (X)GPON, TWDM, etc. 21

22. OTONESONU thin-film optical filter identical for all ONUs“colorless” ONU ! (no tunable or variable parameters filter in ONU) Laserless reflective ONU ! US re-mod of DS light by coherent 16-QAM identical on both X,Y polarizations Y-POL REMOD X-POL REMOD A patent app was filed early in 2010 MIXED-SIGNAL ASIC 22

23. Spectral Design DS DET narrowband filter and detect just one stream ENERGY EFFICIENT MIXED-SIGNAL ONU ASIC ADC/DAC: 156 MHz 417MS/s 23

24. OTONES simulation results ONU PD output, electrical DS @Remote Hub output, RHS slice filtered down DS @ OLT output Ideal 16-QAM SNR=16.5 dB at BER=10-3 2 dB margin US @ OLT input SNR=18.5 dB SNR=18.5 dB ONU DS 16-QAM constellation after max-ratio polarization-diversity combining OLT US16-QAM constellation after max-ratio polarization-diversity combining 24

25. OTONES Network Prototype is currently under implementation • Bi-directional Network simulation using a Matlab-Simulink Model were performed at the Technion • ONU Photonic Integrated Circuit (PIC) – Developed at Karlsruhe Institute of Technology (KIT), Germany, Expected May-’14 • ONU Digital Rx implemented at Technion-IIT, on a Xilinx Virtex-6 chip • OLT Digital Rx, Optical SSB modulator – Implemented at Technion-IIT, expected during Apr-’14 • Proof of concept experiments – planned during Q2 ‘14 PIC mask – courtesy of Philipp Schindler, KIT, Germany 25

26. Conclusions • Self Coherent Detection – Cost effective scheme for spectral efficient low cost optical links • Reflective Modulation – Cost effective scheme for bi-directional transmission in access networks • Both techniques may be applied in future optical access networks (FTTH) 26

27. that’s it 27