1. Making Networks Light
March 29, 2018
Charleston, South Carolina

2. Outline Rationale Efficiency Basic Components Key Innovations
Multiplexing
Trends

3. Rationale- Basis of Competition
Performance.
Reliability.
Convenience.
Price.
From Christensen Innovators Dilemma

4. Internet Use Trends

5. Rationale for Optical Approach
RUDIMENTARY COMPARISON (Miller, Proc. IEEE 97(7) 2009)
Line Capacitance -vs- Detector Capacitance
ELECTRICAL CONNECTIONS
Must charge a line to the voltage of the link:
Energy  (1/2) (Capacitance) (Voltage)2
OPTICAL CONNECTIONS
Since we use photons and detectors, we use signaling voltage:
Energy  (Photon Energy in eV)(Detector Capacitance) (Voltage)
OPTICAL SIGNAL TRANSMISSION TAKES LESS ENERGY:
Governed by photodetector capacitance.
Optical signals are not subject to resistive line loss.

6. Efficiency- present emphasis
Efficiency is measured by the user, and can
be optimized for a just few metrics at once.
SYSTEM METRICS:
Acquisition Cost…
Performance
Manufacturability
Compliance
Reliability
Maintainability
Life Cycle Cost…
NETWORK METRICS:
Cost
Physical Size
Capacity
Bandwidth
Latency
Protocols
Management & Control

7. Fundamental Optical Link
SOURCE- Typical 850 nm 100 Mb, 1 pJ per bit
Typical 1500 nm DWDM Laser, 10 fJ per bit *
MEDIA- Free space, optical waveguide, or optical fiber (< 1 dB per km)
DETECTOR- Typical photodetector, fJ per bit
MODULATOR- Typical modulator, when used, 1 pJ per bit

8. The Link Value Equation
(2 x OEO + Optical Cable) < Electrical Cable

9. Common Optical Fiber MULTIMODE FIBER SINGLE MODE FIBER
Outer Diameter 125 m
Core Diameter 50, 62.5,…m
Core Diameter 5-10 m
Alignment Tolerance 10 m
Alignment Tolerance 1 m
Multiplexing ≤ 10 channels
Multiplexing ≥ 200 channels
Signal Bandwidth ≤ 10 GHz
Signal Bandwidth ≥ 100 GHz
Wavelength 850, 1300 nm
Wavelength nm

10. Common Passive Component

11. Laser Diode

12. Fiber Optic Modulator

13. Optical Amplifier (EDFA)

14. Modulation Formats Amplitude Modulation (analog / RF)
RZ- Return to Zero, ON/OFF
NRZ- Non-Return to Zero, Light on
Phase Modulation- Phase Shift Keying (PSK)
QPSK- Quadrature Phase Shift Keying
Polarization Modulation
Frequency Modulation (analog / RF)
Pulse Amplitude Modulation (PAM)
Practical systems to 64 QAM have been produced (6 bits per symbol), but QPSK (2 bits per symbol) is popular.
PAM 4 is 3X more efficient than NRZ.

15. Key Innovations Low Loss Optical Fiber / Waveguide Semiconductor Laser
High Speed Photodetector
High Frequency Modulators
Wavelength Division Multiplexing
Optical Amplifiers
Temperature Control
Dispersion Compensation and Management
Tunable Filters
Vertical Cavity Surface Emitting Laser (VCSEL)
Large Mode Field Fiber
III-V Integration for Active Devices
Wavelength Converters
Silicon Photonics, Silica / SOI Photonics
Ribbon Cable and Multi-Fiber Connectors
Optical Data Storage and Computational Devices

16. Integration

17. Multiplexing More independent channels in a single fiber-
Optical Code Division Multiplexing (OCDMA)
Time Division Multiplexing (TDM)
Wavelength Division Multiplexing (WDM)
Space Division Multiplexing (SDM)
Multi-Core Optical Fiber
Ribbon Optical Fiber

18. WDM WAVELENGTH DIVISION MULTIPLEXING - Hundreds of channels per fiber.
Standard wavelengths defined by ITU.
Technology established for telecommunications.
Transparent optical backbone.
Five Optical Network Element (ONE)
types perform all functions within
the Optical Backbone Network:
(OXC) Optical Cross-Connect
(OPS) Optical Power Splitter
(OADM) Optical Add/Drop MUX
(OTM) Optical Terminal MUX
(OLA) Optical Line Amplifier
From: Stark, Habiby- Penn State EOC WDM LAN Functional Analysis Project 2008

19. Trends- Hardware Functions

20. Trend- Quantum Encryption
From BBVA-OpenMind

21. Non Electrical Topside (NET)
Corrosion is a significant issue for electrical systems in ships.
Optical fiber is compatible with composite materials.
Optical fiber transmission needs no ground.
Optical fiber does not produce EMI.
Optical fiber can be used for:
Digital data transmission.
Analog / RF signal transmission.
Power delivery <100 watt.
Illumination- LED / laser.
Free space communication.

22. Thank you! John Mazurowski Penn State University
Applied Research Laboratory
Electro-Optics Center
x7139