Datacenter connectivity technologies : principles and practice

Front Cover
Half Title Page
RIVER PUBLISHERS SERIES IN OPTICS AND PHOTONICS
Title Page
Copyright page
Contents
Preface
Acknowledgements
List of Contributors
List of Figures
List of Tables
List of Abbreviations
Chapter 1 - Optical Interconnect Technologies for Datacenter Networks
	1.1 Introduction
	1.2 Intra-datacenter Interconnects
		1.2.1 40G Optical Interconnect Technologies
		1.2.2 100G Optical Interconnect Technologies
		1.2.3 400G and Beyond Optical Interconnect Technologies
	1.3 Inter-datacenter Interconnects
		1.3.1 Inter-datacenter Interconnects in Metro Networks
		1.3.2 Inter-datacenter Interconnects in WANs
	1.4 Summary
	References
Chapter 2 - Vertical Cavity Surface Emitting Lasers
	2.1 Introduction
	2.2 Technology Fundamentals
	2.3 VCSEL Device Structure
	2.4 VCSEL Material Growth
	2.5 VCSEL Fabrication Process
	2.6 Conclusion
	References
Chapter 3 - Directly Modulated Laser Technology: Past, Present, and Future
	3.1 Introduction
	3.2 Intuitive Picture of the Dynamics of Directly Modulated Lasers
	3.3 Progress of High-Speed FP and DFB Lasers
		3.3.1 1.55 mm DML
		3.3.2 1.3 mm DML
		3.3.3 Short-Wavelength DML
	3.4 Reach Extension of DML for PON and Metro Applications
		3.4.1 Principle of Reach Extension of DML by Tailoring Chirp
		3.4.2 10 Git/s Transmission Performance of Adiabatic- and Transient-Chirp Dominant DMLs
		3.4.3 Gain Compression Phenomena
		3.4.4 Experimental S21 Response and Transmission Performance of a Highly-Damped DBR Laser
		3.4.5 Thermal Wavelength Drift Stabilization for the Burst-Mode NGPON2 Application
	3.5 Chirp Managed Laser (CML)
		3.5.1 Principles of CML
		3.5.2 Experimental Demonstrations of CML
	3.6 New Era of High-Speed DML Toward 100-GHz Bandwidth
		3.6.1 Detuned-Loading Effect
		3.6.2 S21 High-Pass Filter Effect Due to In-Cavity FM-AM Conversion by the DBR Mirror
		3.6.3 Photon-Photon Resonance Effect
		3.6.4 Co-Existence of Photon-Photon Resonance and Detuned-Loading Effects
		3.6.5 55-GHz Bandwidth Short-Cavity DR Laser and 56 Gbaud PAM4 Generation
	3.7 Conclusions
	Acknowledgements
	References
Chapter 4 - PAM4 Modulation Using Electro-absorption Modulated Lasers
	4.1 Introduction
	4.2 General PAM4 Optical Transceiver and Link Considerations
		4.2.1 PAM4 Signal and Optical Link Characteristics
		4.2.2 EML Biasing and Nonlinear Equalization
		4.2.3 Forward Error Correction (FEC) and Data Rates for PAM4 Links
		4.2.4 Sampling Rate and Analog Bandwidth
		4.2.5 FFE and DFE Equalization
	4.3 28 Gbaud PAM4 Transmission [16, 17]
	4.4 56 Gbaud PAM4 Transmission over 2 km Experiment
	4.5 40 km PAM4 Transmission
		4.5.1 Avalanche Photodiode (APD)
		4.5.2 Gain Clamped Semiconductor Optical Amplifier (GC-SOA)
	4.6 100 km PAM4 Transmission
		4.6.1 Experimental Setup
		4.6.2 Single Channel Characteristics
		4.6.3 Effect of Fiber Nonlinearities
	4.7 Multipath Interference [34, 35]
		4.7.1 Experimental Demonstration of the Upper Bound MPI Scenario
		4.7.3 MPI Experiment with Multiple Connectors
		4.7.2 Time-Domain Mixing Monte Carlo Simulation
	4.8 Summary
	References
Chapter 5 - Optical Fiber for Datacenter Connectivity
	5.1 Introduction
	5.2 Fiber Type for Datacenters
		5.2.1 Multimode Fiber Types for Datacenters
		5.2.2 Single-mode Fiber Types for Datacenters
		5.2.3 Optical Cabling for Datacenters
		5.2.4 Multicore (MCF) and Few-Mode Fiber (FMF) for SDM
	5.3 Waveguide Design, Modal Structure, and Time Response of SMF and MMF for Datacenters
		5.3.1 Fundamentals of Waveguide Design and Mode Structures of SMF and MMF
		5.3.2 Fundamentals of the Time Response of Optical Fiber
	5.4 Multimode Optical Fiber for High-Speed Short-Reach Interconnect
		5.4.1 Laser-optimized MMF (OM3 and OM4)
			5.4.1.1 What is Laser-optimized MMF?
			5.4.1.2 Differential Modal Delay (DMD)
			5.4.1.3 Bandwidth of MMF Links
				5.4.1.3.1 Overfilled modal bandwidth
				5.4.1.3.2 Effective modal bandwidth
				5.4.1.3.3 Chromatic bandwidth
				5.4.1.3.4 True bandwidth of a short-reach interconnect system channel
		5.4.2 Bend-optimized OM3/OM4 and Overfilled Effective Modal Bandwidth
		5.4.3 Wideband MMF (OM5)
	5.5 High-Speed VCSEL-MMF Short-Reach Optical Interconnect System
		5.5.1 System Evaluation Methodology
		5.5.2 High-Speed VCSEL-MMF System Transmission Validation
			5.5.2.1 10GBASE-SR transmission over OM3 and OM4 MMF
			5.5.2.2 40GBASE-eSR4 and 100G eSR4 extended reach demonstration over OM4 MMF
			5.5.2.3 40/100 Gbps SWDM over OM5 MMF
			5.5.2.4 High-Speed PAM4 SWDM transmission over OM5 MMF
	5.6 Datacom Transmission over Single-Mode Optical Fiber
	5.7 Conclusions
	Acknowledgement
	References
Chapter 6 - PAM4 Signaling and its Applications
	6.1 Introduction
	6.2 A Brief History
	6.3 PAM4 IC Implementation Challenges
		6.3.1 PAM4 Transmit Architectures
		6.3.2 PAM4 Receive Architectures
	6.4 PAM4 SMF Performance
		6.4.1 Experimental Setups
		6.4.2 1 40G 10 km Transmission
		6.4.3 2 100G 10 km and 40 km Transmissions
		6.4.4 Technical Options for 200/400G Over SMF
	6.5 PAM4 MMF Performance
		6.5.1 Experimental Setups
		6.5.2 1λ 40G Transmission Over 550m OM4
		6.5.3 2 100/200 Gbps 300m Transmission
		6.5.4 Technical Options for 200/400G Over VCSEL/MMF
	6.6 PAM4 for OSNR-limited Systems at 1550 nm
		6.6.1 Experimental Setups
		6.6.2 OSNR and Dispersion Performance
	6.7 PAM4 Compliance Tests
		6.7.1 Transmitter Dispersion Eye Closure for PAM4 (TDECQ)
		6.7.2 Optical Stressed Receiver Sensitivity
	6.8 Single Lambda PAM4
	6.9 Summary and Outlook
	Acknowledgements
	References
Chapter 7 - Discrete Multitone for Metro Datacenter Interconnect
	7.1 Introduction
	7.2 A Brief History of DMT
	7.3 How DMT Works
		7.3.1 FFT/IFFT
		7.3.2 Cyclic Prefix
		7.3.3 Loading Algorithm
		7.3.4 PAPR Suppression
		7.3.5 Synchronization
		7.3.6 Channel Equalization
	7.4 Advanced DMT Techniques for Metro DCI
		7.4.1 The Principle of CD-induced Power Fading
		7.4.2 Generations of SSB-DMT
			7.4.2.1 Optical filter-based SSB-DMT
			7.4.2.2 E/O modulator-based SSB-DMT
				7.4.2.2.1 DD-MZM-based SSB-DMT
				7.4.2.2.2 IQ-MZM-based SSB-DMT
		7.4.3 Generation of EDC-DSB-DMT
		7.4.4 Generation of Twin-SSB-DMT
		7.4.5 Generation of SSBI-free Twin-SSB-DMT
	7.5 Summary
	References
Chapter 8 - A Duobinary Approach Toward High-speed Short-reach Optical Interconnects
	8.1 Introduction
	8.2 Three-Level Electrical Duobinary Modulation
		8.2.1 Nyquist Frequency
		8.2.2 Power Spectral Density
		8.2.3 Vertical and Horizontal Eye Openings
	8.3 100-Gbps EDB/NRZ Transmitter and Receiver Chipset
	8.4 EDB/NRZ Transmission with DFB-TWEAM
	8.5 NRZ-OOK Transmission with GeSi EAM
	8.6 SM LW-VCSEL EDB Links
	8.7 Conclusion
	Acknowledgment
	References
Chapter 9 - LiNbO3 Mach-Zehnder Modulator
	9.1 Introduction
	9.2 Physical Properties of LN (LiNbO3) Crystal
	9.3 Low-loss Ti-diffused Waveguides on LN Since 1974
	9.4 Mach–Zehnder (MZ) Guided-wave Circuit with Y-branches on LN
	9.5 Velocity Matching Between Lightwaveand Electric Signal
	9.6 Stabilization of LN-MZM Operation
	9.7 External Modulation by LN-MZM Accompanied with EDFA Repeating
	9.9 Current Status of LN-MZM and Future Potential
	9.8 Vector Modulation with LN-MZM for Digital Coherent Optical Communications
	9.10 Summary
	References
Chapter 10 - Silicon Photonics Based PAM4, DWDMDatacenter Interconnects
	10.2 Datacenter Interconnect–Edge
	10.1 Introduction
	10.3 Switch Pluggable 100Gbit/s DWDM Module
	10.4 PAM4 DSP ASIC
	10.5 Silicon Photonics
	10.6 Module and Transmission Performance
	10.7 Live Datacenter Deployments
	10.8 Evolution to Switch Pluggable 400-Gbit/s DWDM Module
	10.9 Conclusion
	Acknowledgments
	References
Chapter 11 - Low-Loss Photonic Integration: Applications in Datacenters
	11.1 Datacenters and Photonic Integrated Circuits
	11.2 InP, Si, and Si3N4 Waveguide Platforms
	11.3 The Ultra-Low Loss Si3N4/SiO2 Platform
	11.4 Integration Building Blocks on the ULL Silicon Nitride Platform
		11.4.1 Available PIC Platforms
	11.5 Ultra-Low Loss PIC Components for Datacom
		11.5.1 Low-Loss PICs and Optical Delays
		11.5.2 Integrated Dispersion Compensation
			11.5.2.1 Design of an Integrated Dispersion Compensator
			11.5.2.2 Demonstration of 40 Gbps NRZ-OOK Dispersion Compensation
			11.5.2.3 Demonstration of 40 Gbps PAM-4 Dispersion Compensation
		11.5.3 Grating Filters
		11.5.4 Ring Resonator Filters
		11.5.5 High-Extinction Filters
		11.5.6 C-band Lasers on the Si3N4 Platform
	11.6 Silicon-Nitride Waveguide Design
	11.7 Summary
	Acknowledgements
	References
Chapter 12 - Advanced Optical Measurementsfor Data Centers
	12.1 Introduction
	12.2 Polarization Related Tests
		12.2.1 Polarization Mode Dispersion (PMD) Measurement
		12.2.2 Polarization Dependent Loss (PDL) Measurement
		12.2.3 PDR Measurement of Receivers
		12.2.4 PDL Measurement of Fiber Optic Link
		12.2.5 Measuring In-band OSNR by DOP Measurement
		12.2.6 Polarization Emulation for Non-coherent and Coherent Systems
	12.3 Optical Signal-to-Noise Ratio Measurement
		12.3.1 Measuring OSNR with an OSA
	12.4 Characterization of Optical Vector-Modulated Signals
		12.4.1 Constellation and IQ Diagrams for Vector-Modulated Signal
		12.4.2 Definitions of EVM, RMS-EVM and TR-EVM
		12.4.3 Relationships between EVMRMS, Q-Factor, OSNR and BER
		12.4.4 Characterization of Transmitter Impairments
	12.5 Conclusion
	Acknowledgements
	References
Chapter 13 - Digital Signal Processing for Short-reach Optical Communications
	13.1 Introduction
		13.1.1 Challenges for Short-reach Optical Systems
			13.1.1.1 Cost
			13.1.1.2 Form factor
			13.1.1.3 Latency
		13.1.2 Different Types of Short-reach Systems
			13.1.2.1 Server-to-server or Intra-data-center links
			13.1.2.2 Inter data-center links
			13.1.2.3 Extended Reach Inter-data-center, Access,and Metro Links
	13.2 Modulation Formats for Short-reach Systems
		13.2.1 Pulse Amplitude Modulation (PAM)
		13.2.2 Carry-less Amplitude and Phase (CAP) Modulation
		13.2.3 Discrete Multi-tone (DMT) Modulation
		13.2.4 Performance Comparison of Modulation Formats
		13.2.5 Complexity Comparison of Modulation Formats
		13.2.6 Recent Experiment on High-Speed Short-reachTransmission SystemsBased on those high-order modulatio
	13.3 Digital Signal Processing for Short-reach Systems
		13.3.1 Feed-forward Equalizer (FFE)
		13.3.2 Decision Feedback Equalizer (DFE)
		13.3.3 Direct Detection Faster-than Nyquist (DD-FTN)
		13.3.4 Volterra-series Based Nonlinear Equalizer (VNLE)
	13.4 Polarization Division Multiplexed Transmissionfor Short-reach Systems
		13.4.1 Stokes-vector Direct Detection (SV-DD) Receiver
		13.4.2 2-Dimensional (2D) PDM-DD System Basedon SV-DD Receiver
		13.4.3 3-Dimensional (3D) PDM-DD System Based on SV-DD Receiver
	13.5 Conclusion
	Acknowledgments
	References
Chapter 14 - Multi-dimensional Polarization Modulation
	14.1 Optical Detection with Polarization Diversity
		14.1.1 The Need of Polarization-Diversity Detection
		14.1.2 Automatic Polarization Control
		14.1.3 Polarization-Diversity Detection in Jones Space
		14.1.4 The Barrier of Self-Polarization Diversity
		14.1.5 Polarization-Diversity Detection in Stokes Space
	14.2 Direct Modulation with Coherent Receiver
		14.2.1 The Intensity-only POL-MUX-DM Coherent System
		14.2.2 Complex DM Model
		14.2.3 100-Gb/s CDM Transmission Over 1600-km SMF
	14.3 Polarization Modulation in Stokes Space
		14.3.1 Stokes-space Modulation
		14.3.2 Universal MIMO Equalization in Stokes Space
		14.3.3 Self-coherent SSM
		14.3.4 Multi-Dimensional IM in Stokes Space
	14.4 Noncoherent Polarization Multiplexing
		14.4.1 Degree of Coherence in POL-MUX Transmitter
		14.4.2 Noncoherent POL-MUX Schemes
	14.5 Summary
	References
Chapter 15 - High-speed Flexible Coherent Optical Transport Network
	15.1 Introduction
	15.2 Why Optical Coherent Transmission?
	15.3 Optical Transport Network with Coherent Transmission
	15.4 What’s Next for Optical Transport Network?
	15.5 Coherent Transport Technology Development by Network Operators
	15.6 Datacenter Connections and Coherent Transport Networks
	15.7 Conclusions
	References
Chapter 16 - Ultra-low-power SiGe Driver-IC for High-speed Electro-absorption Modulated DFB Lasers
	16.1 Introduction
	16.2 IC Design for Low Power Consumption
		16.2.1 Design Requirements
		16.2.2 IC Architectures for Low Power Consumption
		16.2.3 Driver-IC Design
			16.2.3.1 Unit-cell design
			16.2.3.2 Circuit Simulations
	16.3 Co-design and Electro-optical Simulation
		16.3.1 Low-power CoC Design
		16.3.2 Co-simulation of Driver-IC with EML
			16.3.2.1 Electrical Time-domain Simulations
			16.3.2.2 Electro-optical Time-domain Simulations
	16.4 Measurements
		16.4.1 EO Measurements
		16.4.2 Transmission Experiments [7]
	16.5 Conclusion and Perspective
	Acknowledgments
	References
Index
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