infinera 100g beyond wade

8/9/2019 Infinera 100G Beyond Wade

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Advanced Modulation For High

Data Rate Optical Transmission:

100G and Beyond

Leigh Wade, Infinera


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The State of the Market Today

800G•

10Gb/s• NRZ

• C-band

80 ch. @ 10G = 800G

Morechannels

HigherData Rates

MoreSpectrum

I will propose that photonic integration is an excellent solution to all three

capacity challenges


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Why do we needmore than 800G?

Lower Cost per Bit

More Capacity

Higher Speed Services


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Fiber Exhaust & Network Economics

C o s t p e r U s a b l e B i t

Time

10G λ

40G λ

100G λ

You want to move

to 40G here…

…but what if you hit

fiber exhaust here?

Excess

cost

Fiber exhaust can force uneconomic network decisions


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Double Density Optics Mean Investment Protection

and “Option Value”

Conventional 80-96 λ WDM

1 λ per 50 GHz

At 40% bandwidth growth, double-density optics mean

two more years to select the lowest cost transmission.

Infinera “Double Density” WDM

1 λ per 25 GHz

800G in the C-band 1.6T in the C-band


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Why doesn’t everybody offer Double Density?

Two basic reasons:

WSS ROADMs

designed

around 50GHz

spacing

Operational challenge of 160 discrete

transponders on a single fiber!!


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What are you going to see?

Adding a single PIC-based line card, with

10x10Gb/s waves

100Gb/s of capacity for

the same effort as one10Gb/s transponder

Optical

Spectrum

Analyzer

Stopwatch

Existing 10G waves

on the fiber

“Gaps” for

additional waves


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PICs reduce operational burden by 10x

But the rest of the optical industry

does not have access to PICs so…

They are under pressure to move to

40G and 100G as soon as possible

Not necessarily when it’s economical!


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Fiber Capacity

AdvancedModulation

CoherentDetection

High Gain FEC

Table

Stakes

Core Switching & Grooming3

Large Scale PICs2

Photonic Integration1

Differentiators

100G Technology Features


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Complex modulation requirescomplex optical circuits


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Why do I need Complex Modulation?

Optical transmission is about:• Sending high data rates

• Over very long distances

• For very little money

Our biggest problem is optical fiber:• Loss

• Dispersion

• Modal dispersion

• Chromatic dispersion

•

Polarization mode dispersion• Non-linear effects

• Self phase modulation

• Cross phase modulation

• Four wave mixing

If you stress any one of these variables, the

others will respond

For a given modulation type, the

gross magnitude of these

impairments scales roughly withthe square of the symbol rate


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Think of a light wave...

Oscillating wave

Wavelength• 1550nm

Frequency• 193.1 THz

“State of the shelf”

electronics can process at

~10GHz

Electronics is about 20,000 times

“too slow” for direct detection of

“wave properties”

h d d d d l


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So how do we encode and detect signals on

an optical carrier?

Historically, used amplitude modulation

Measures the strength of a large number of waves

On/Off Keying (OOK) may interpret the presence of asignal as a “1”, and the absence of a symbol as a “0”


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1 bit per symbol: NRZ Modulation

Laser Modulator

Detector

Tx

Rx

NRZ

Simple modulation technique

Easy to implement

Low power use

But very sensitive to fiber impairments

as bitrate increases• This is what we’re talking about with the “square”

relationship

Increasing power will trigger non-lineareffects


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Phase Shift Keying

Phase is fundamental property of waves• Two waves in-phase when the peaks & troughs line up

• We say that such waves are coherent

• If non-coherent waves combine we see:

• Reinforcement, cancellation, interference

Interference can be used to extract a lower frequencymodulation from a high frequency carrier

In-phase Out of phase Interference

patterns


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Using Phase to Apply a Signal

LD

Laser generates aconstant carrier

The carrier is

split into 2

The carriers travel

over different paths

S

Can apply a data signal,

S, to vary the delay on

one of the arms

When the carriers

recombine they will

“contain” the data signal

encoded as a series of

phase changesTx

Rx Q: How do we recover the data signal at the receiver?Hold that thought!

MZI


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Component Complexity

Tx Rx

Part 1

The Transmitter


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ODB Modulation (Optical Duo-Binary)

Laser MZ Modulator

Detector

Tx

Rx

ODB

First generation 40G modulation scheme Phase & Amplitude based modulation

• Requires MZ modulator

• Can use simple, direct detection

Much more tolerant of dispersion Limited reach

Widely used by 1st Gen 40G• Stratalight, Mintera


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1 bit per symbol: DPSK

Most basic phase modulation technique

Differential technique allows phase slips to be ignored

Used by OpNext & Mintera, and their OEMs

AKA: BPSK, where local oscillator coherent detection is used

Re{Ex}1 0


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2 bits per symbol: Quadrature PSK

Advanced modulation, 4 phase states = 2 bits More bits per symbol


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2 bits per symbol: Quadrature PSK

Advanced modulation, 4 phase states = 2 bits More bits per symbol

0,0

0,1

1,1

1,0

3 bi b l 8 PSK


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3 bits per symbol: 8-PSK...And higher orders of modulation

8 phase states = 3 bits Twice as complex, but only 50% more bits

1,0,0

0,0,1

1,1,0

1,0,10,0,0

0,1,1

1,1,1

0,1,0

For discrete implementations, 8-PSK seems to be too complex

Th L f Di i i hi R


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The Law of Diminishing Returns

Phase States vs Component Complexity

Let’s set a circuit complexity factor of 1, to be theequivalent of a simple DPSK transponder

DPSK (D)QPSK 8-PSK 16-QAM 32-QAM 64-QAM

16x

Bit/Hz

9

8

7

6

5

4

32

1

9

8

7

6

5

4

32

1

C o

m p l e x i t y F a c t o r

Is there a better way to

get to more bit/Hz?

32x


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PM-QPSK, 4 bits per “symbol”

Im{Ex}

Re{Ex}

Im{Ex}

Re{Ex}

Im{Ey}

Re{Ey}

Two Polarizations

X-Polarization

Y-Polarization

I l ti Ph M d l ti U i Di t


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Implementing Phase Modulation Using Discrete

Optical Components...

S

I l ti Ph M d l ti U i Di t


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S

Implementing Phase Modulation Using Discrete

Optical Components...


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This is a PM-QPSK Transmitter

PBSLD

X Polarizations

Y Polarizations


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Component Complexity

Tx Rx

Part 2

The Detector


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Let’s cut to the chase…

The only practical, long haul 100G implementations will

be required to use Coherent Detection

What is it, and why is it useful?


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What is “coherent detection”?

Physics definition• A detection technique that is based on the phase properties

of the carrier

• If you are using a phase-based detector, you could claim to

be implementing coherent detection

…however…

Practical definition

• The market has now come to expect a “coherent detector” to

make use of sophisticated, digital signal processing (DSP)

algorithms


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Conventional WDM Detection

PD

Mixture of waves on fiber… …wideband detector

How do we select the

channel we want to detect?


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Wavelength demux

PD

Mixture of waves on fiber… …wideband detector


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Direct conversion

of photons into

electrons that

“look like” bits

…11010110…


Wavelength demux

PD


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Summary of “Conventional WDM Detection”

Wideband Photodetector (PD) is used

To prevent inter-channel interference, a wavelength

demux is used to spatially separate channels

Modulation technique allows minimal Rx circuit

complexity – essentially “direct detection”

No additional signal processing normally required


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ADC DSP

Coherent WDM Detection

PDLO

We could take a mixed signal that uses a phase-based modulation technique

Use a local oscillator to choose the

“color” we want to “detect”


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ADC DSP

Coherent WDM Detection

PDLO …11010110…

Convert the

photons to

electrons

Convert the“analog electrons”

into “digital

electrons”

Clean it all up!

Wh h b d d l ti ?


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If you need to detect 5 from 1…n, then choose alocal oscillator tuned to 5

Local oscillator does not carry a signal – simply acontinuous beam of light

But it is non-coherent with the received signal (ie. it isout of phase)

Use an array of interferometers to “measure” theinterference patterns

Convert the interference patterns into an electronicsignal, and “process it”

Why phase-based modulation?

The Detector Requires a Complex Optical Circuit


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The Detector Requires a Complex Optical CircuitExample: For PM-QPSK Modulation…

PBS

LO PBS

PD

PD

PD

PD

The signals that come

out of the PD array are

“analog and dirty”

PM-QPSK Signal

ff f


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Two very different functions in the detector

Phase state

extraction

Signal processing

• Separate the polarization components

• Create interference against a

reference laser (local oscillator)

• Separate the phase components

• PD & A/D conversion

• Compensate for local oscillator

instability

• Compensate for static CD

• Compensate for dynamic PMD

d l h f ?


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How do we implement these functions?

• Separate the polarization components

• Create interference against a

reference laser (local oscillator)

• Separate the phase components

• PD & A/D conversion

• Compensate for local oscillator

instability

• Compensate for static CD

• Compensate for dynamic PMD

Sophisticated

optical circuit

(PIC)

Sophisticated digital

signal processing(DSP)

A Coherent Detector Schematic


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(For one wavelength only)

Incoming carrier

(2 polarizations, each

with 4 phase states)

ADC A/D Converter

AMZ Adjustable Mach Zehnder

DSP Digital Signal Processor

LO Local Oscillator

PD Photo Detector

PS Polarization Splitter

LO

PD

PD

PD

PD

ADC

ADC

ADC

ADC

D S P

AMZ

AMZ

AMZ

AMZ

Optical Circuit Electronic Circuit

PBS

PBS



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Incoming carrier



LO

PD

PD

PD

PD

ADC

ADC

ADC

ADC

D S P

AMZ

AMZ

AMZ

AMZ


PBS

PBS

ADC A/D Converter



LO Local Oscillator

PD Photo Detector


1

Step 1: Take the two optical sources – signal and local oscillator

A Coherent Detector Schematic(For one wavelength only)



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Incoming carrier



LO

PD

PD

PD

PD

ADC

ADC

ADC

ADC

D S P

AMZ

AMZ

AMZ

AMZ


PBS

PBS

ADC A/D Converter



LO Local Oscillator

PD Photo Detector


2

Step 2: Separate the X and Y polarizations




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Incoming carrier



LO

PD

PD

PD

PD

ADC

ADC

ADC

ADC

D S P

AMZ

AMZ

AMZ

AMZ


PBS

PBS

ADC A/D Converter



LO Local Oscillator

PD Photo Detector


3

Step 3: Generate a set of interference patterns in the SMZ array




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Incoming carrier



LO

PD

PD

PD

PD

ADC

ADC

ADC

ADC

D S P

AMZ

AMZ

AMZ

AMZ


PBS

PBS

ADC A/D Converter



LO Local Oscillator

PD Photo Detector


4

Step 4: Convert optical signals to analog electronic signals

Co e e t etecto Sc e at c(For one wavelength only)



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Incoming carrier



LO

PD

PD

PD

PD

ADC

ADC

ADC

ADC

D S P

AMZ

AMZ

AMZ

AMZ


PBS

PBS

ADC A/D Converter



LO Local Oscillator

PD Photo Detector


5

Step 5: Convert analog to digital and process

(For one wavelength only)

C h t D t ti P d C


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Coherent Detection – Pros and Cons

Pros:• Operates over the existing fiber plant and amp chains

• Outstanding reach performance

• Closest thing to achieving 40G and 100G with same reach as 10G NRZ

• Significant pilot test results indicate it really does work!

Cons:• Potential non-linear interaction with 10G NRZ in same fiber

• The “cure” is managing launch power

• Probably represents the practical complexity limit for discretes

• State of the shelf DSP technology draws too much power to allow for largescale implementations (ie. multiple waves in one modules)

• Solution is to use emerging 40µm DSP technology

• DSP operation probably eliminates the chance of future line side interop

So remember


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Complex modulation requirescomplex optical circuits

So remember…

Wh h thi bl b f ?


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Where have we seen this problem before?

In the 1950s computers were made from individualtransistors, resistors and capacitors...

…today?

http://images.google.com/imgres?imgurl=www.toroid.se/inductor.jpg&imgrefurl=http://www.toroid.se/prod.htm&h=183&w=276&prev=/images?q=inductor&svnum=10&hl=en&lr=&ie=UTF-8&oe=UTF-8http://images.google.com/imgres?imgurl=www.suntan.com.hk/Metallized%20Polycarbonate%20Film%20Capacitor.jpg&imgrefurl=http://www.suntan.com.hk/product.html&h=286&w=413&prev=/images?q=capacitor&start=40&svnum=10&hl=en&lr=&ie=UTF-8&oe=UTF-8&sa=Nhttp://images.google.com/imgres?imgurl=www.acte.dk/pages_dk/produkter/billeder/capacitor.gif&imgrefurl=http://www.acte.dk/pages_dk/produkter/yageo.asp&h=140&w=180&prev=/images?q=capacitor&svnum=10&hl=en&lr=&ie=UTF-8&oe=UTF-8


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The electronics industry controlled component

complexity with large scale integration

We know the same thing works for optical

components – we did it 5 years ago!

Small Scale vs Large Scale Photonic Integration


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Small Scale vs Large Scale Photonic Integration

Small Scale… • Operates on a single wavelength

• Primarily used to address manufacturing cost

If it works for one wave, why not…

CPUs with 2-8 cores GPUs with 200-800 cores!!

Infinera 100G Transmission Differentiators


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500G, Large Scale, Monolithic PIC Implementation

500G

Tx PIC

500G

Rx PIC

Number of channels 5 x 100G

Monolithic InP Chips 2

Optical elements > 600

“Gold Box” Replacements > 100

Fiber Replacements > 400

COSTSIZE

POWERCAPACITY

RELIABILITY

54 © 2011 Infinera Corporation Confidential & Proprietary


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How much capacity can

actually be used?

Fat Pipes Are Not Enough



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100 Gb/s Transmit

100 Gb/s Receive

PICs enable

cost-effective OEO

100Gb/s to 1Tb/s “WDM

system on a chip”

Affordable access to

digital domain

Photonic

Integration


PICs Enable Pervasive Digital Switching



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1001

0101

0101

1010

1101

0101

0101

1010

1101

0101

Enables “digital” functionality

Integrated switching at every node

High functionality Digital ROADM

Dramatic network simplification

100101011101010000101011

100101010101101011010101

110101000010101110010101

001010111011010110010101

I n t e g r a t e d P h o t o n i c s


Optical (O) Electrical (E) Optical (O)

Trib

Integrated

Switching + WDM

Photonic

Integration





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1001

0101

0101

1010

1101

0101

0101

1010

1101

0101

100101011101010000101011

100101010101101011010101

110101000010101110010101

001010111011010110010101



Pervasive Digital

Switching

Integrated

Switching + WDM

Photonic

Integration

10010101110101010000

10010101010110101011

10010101110101010000

10010101010110101011end-end service

Software-based “Ease-of-Use”

Digital OTN switching at every node

Unconstrained bandwidth everywhere

Lowest cost per switched Gb/s



Solving The 100G Muxponder Tax


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Solving The 100G Muxponder Tax

The Problem:• Backbone waves move to 100G, but service demands still 10G or lower

• All-optical ROADMs have no inter-wavelength, or sub-wavelength

grooming capability → 100G muxponders!

How big is the

“Muxponder Tax”

in a real 100G

network?

A BAll services must go A ↔B

10GbE

10GbE

10GbE

M u x p o n d e r

10GbE

M u x p o n d e

r

ROADM Network

A C↔

A D↔

B C↔

B D↔

Require Extra,Partially Filled

Muxponder Pairs

Service Demands:

© 2011 Infinera Corporation Confidential & Proprietary59

Infinera National Network Model Summary


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10090

80

70

60

5040

30

20

10 D e p l o y e d C a p a c i t y ( % )

R e v e n u e G e

n e r a t i n g ( % )100

90

80

70

60

5040

30

20

10

100G

Muxponder

50%

40G

Muxponder

66%

Infinera Digital

ROADM

92%

Infinera National Network Model Summary

• Large N. Am. Network Model: 33,084 route km, 47 core WDM links

• About 10 Tb/s of customer service demands (network traffic volume)


Summary of Network Efficiency


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Summary of Network Efficiency

A “Perfect Storm” is emerging in terms of network

bandwidth efficiency:• Wavelength speeds moving to 100Gbit/s

• Majority of services demands remaining at 10Gbit/s or less for near-term

• All-optical ROADMs have no effective way to offer contentionlesswavelength conversion and sub-wavelength grooming in the core

• Muxponders are simply point-point aggregators and do not do grooming

The result is that a Service Provider may need topurchase 2X Network Capacity for 1X Service Revenue

The solution is an Integrated Digital OTN Network with:• End to End, Any to Any service capability

• Integrated OTN switching and grooming in the core

• End to End intelligent optical control plane

Bandwidth

Virtualization

Beyond 8Tb/s?


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8Tb/s

Morechannels HigherData Rates MoreSpectrum

Beyond 8Tb/s?

Gridless Super-Channels

Even more complex

modulation!

L-Band

S-BandE-Band

O-Band

Outside the scope of this discussion

What’s changed so far


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What s changed so far

Since the advent of DWDM…

now

Phase Modulation

Coherent Detection

ITU Frequency Grid

Intensity Modulation

Direct Detection

ITU Frequency Grid


What Comes Next For Terabit Transport?


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…so what has to change

Phase Modulation

Coherent Detection

ITU Frequency Grid

Intensity Modulation

Direct Detection

ITU Frequency Grid

Quadrature AmplitudeModulation (QAM)

Coherent Wave Combiningand Separation

Grid-less FlexChannels


Advanced Modulation Formats


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Advanced Modulation Formats

Pol-Mux

QPSK Pol-Mux

8-QAM

Pol-Mux

16-QAM

IM-DD

PM-

BPSK

1.6 8 12 16 24

C-Band Capacity (Tb/s)

0

0.2

0.4

0.6

0.8

1

1.2

C a p a c i t y

*

R e a c h P

r o d

u c t




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Quadrature AmplitudeModulation

Coherent Wave Separation


On-Off Keyed Modulation

Direct Detection

ITU Frequency Grid



Single Carrier vs Multi-Carrier


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Single Carrier vs Multi Carrier

Goal: Create a 1Tb/s unit of transmission capacity

How?

Option 1:

Build a single-

carrier 1Tb/s

channel

Option 2:

Build a multi-

carrier 1Tb/s

“super-channel”

1Tb/s Single Carrier: The A/D Converter Problem


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1Tb/s Single Carrier: The A/D Converter Problem

1 2 4 6 8 10 12

1

2

3

4

5

6

7

8

910

O S N R P e n a l t y ( d B )

Number of bits per symbol

PM-BPSK640GBaud

PM-QPSK320GBaud

PM-8QAM210GBaud

PM-16QAM160GBaud

PM-32QAM

128GBaud

PM-64QAM105GBaud

By 2014 commercial ADCs are

expected to operate at ~64GBaud

DWDM Direct Detection


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wavelengthdemux

DWDM Direct Detection

PD

Spacing on the fiberneeded between waves:

“Guard Bands”

Spatially separate the

channels using awavelength demux


DWDM Coherent Detection


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wavelengthdemux

Spatially separate the

channels using awavelength demux

DWDM Coherent Detection

Spacing on the fiberneeded between waves:

“Guard Bands”

ADC DSPPDLO

Use a local oscillator tochoose the “color” we want

to “detect” to match thedemux port color


How 1Tb/s Might Look… C i l WDM Fl Ch l


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Conventional WDM vs FlexChannels

Guard bands to allow for

individual wavelength demux

Fewer guard-bands

25% increase in useable

amplifier spectrum

Conventional Per-Channel

WDM Filtering

1Tb/s

Multi-Carrier FlexChannel

1Tb/s




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Quadrature AmplitudeModulation

Coherent Wave Separation


On-Off Keyed Modulation

Direct Detection

ITU Frequency Grid


FlexChannels Increase Total Fiber CapacityM l d l ti → it fib


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More complex modulation → more capacity per fiber

PM-QPSK

8-QAM

16-QAM

1Tb/s

12 Tb/s

18 Tb/s

25 Tb/s


Reach, Spectral Efficiency, and Co-Existence


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Reach, Spectral Efficiency, and Co Existence

1Tb/s PM-8QAM

FlexChannel

1Tb/s PM-16QAM

FlexChannel10x100G PM-QPSK

1Tb/s PM-QPSK

FlexChannel

or

A

E

B C

D


Summary:Th K T h l i F 1Tb/ A W ll U d t d


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The Key Technologies For 1Tb/s Are Well Understood

But the implementation of those technologies will be

critical to allowing service providers to differentiate theirproducts and services

Advanced

Modulation

Coherent

Processing

Advanced

FEC

Foundation

Features

Large Scale PICs1

FlexCoherent™ Modulation 2

Pervasive, Switched DWDM3

Differentiators



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Thank [email protected]

infinera 100g beyond wade

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