Fiber Optics John Swienton Fiber Geek - JDSU [email protected].

Fiber Optics

John Swienton

Fiber Geek - JDSU

[email protected]

© 2007 JDSU. All rights reserved. JDSU CONFIDENTIAL & PROPRIETARY INFORMATION2

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Business Segments

Communications & Commercial Optical Products

Communications

Test & Measurement

Advanced Optical Technologies

Total Market Size (Annual)*

$3.9B $2.8B $1.5B

Annual Growth Rate* 5-15% 6-12% 5-10%

JDSU Market Position*

#1-2 #1-2 #1-2

MarketsTelecom, Datacom, Submarine,

Long Haul, Metro, Access, Biotech, Microelec,

Telecom/Cable Access, Metro, Core & Home Networking

Currency, Defense Authentication, Instrumentation

Sample

Customers

Alcatel-Lucent, ASML, Becton Dickinson, Ciena, Cisco, Ericsson, ESI, KLA Tencor, Tellabs, Huawei,

Nortel, NSN, Fujitsu

Alcatel-Lucent, AT&T, British Telecom, China Telecom, Comcast, Telmex, Verizon

Abrisa, Bank of China, Dolby Laboratories, ITT, Lockheed Martin,

Pfizer, SICPA

* Sources: Central Banks, Frost & Sullivan, Infonetics Research, Ovum-RHK, PIRA Research, Prime Data, US Chamber of Commerce, and internal analysis.


Measurements and Scales


Light Measurements


Scales


Fiber Review


Optical Fiber


Optical Fiber Types

2 types:– Singlemode– Multimode


Multimode Fiber – Denoted by an Orange Jacket


Single Mode Fiber - SMF


9125250

Cross section of an Single Mode optical fiber


Refraction


n = c / v

n = refractive indexc = velocity of light in a vacuumv = velocity of light in glass

IOR = Index of Refraction


Reflection


Light in an optical fiber – Total Internal Reflection


Bending


Common Connector Types

SC Commonly referred to as Sam Charlie

FC Commonly referred to as Frank Charlie

ST Commonly referred to as Sam Tom

LC Commonly referred to as Lima Charlie


Connector Configurations

PC or UPC vs APC

SC - PC

SC - APC


IBYC


Focused On the Connection

Bulkhead Adapter

Fiber Connector

Alignment Sleeve

Alignment Sleeve

Physical Contact

FiberFerrule

Fiber connectors are widely known as the WEAKEST AND MOST

PROBLEMATIC points in the fiber network.


What Makes a GOOD Fiber Connection?

Perfect Core Alignment

Physical Contact

Pristine Connector Interface

The 3 basic principles that are critical to achieving an efficient fiber optic

connection are “The 3 P’s”:

Core

Cladding

CLEAN

Light Transmitted


What Makes a BAD Fiber Connection?

A single particle mated into the core of a fiber can cause significant back reflection, insertion loss and even equipment damage.

Visual inspection of fiber optic connectors is the only way to determine if they are truly clean before mating them.

CONTAMINATION is the #1 source of troubleshooting in optical networks.

DIRT

Core

Cladding

Back Reflection Insertion LossLight


Illustration of Particle Migration

Each time the connectors are mated, particles around the core are displaced, causing them to migrate and spread across the fiber surface.

Particles larger than 5µ usually explode and multiply upon mating.

Large particles can create barriers (“air gap”) that prevent physical contact.

Particles less than 5µ tend to embed into the fiber surface creating pits and chips.

11.8µ

15.1µ

10.3µ

Actual fiber end face images of particle migration

Core

Cladding


Types of Contamination

A fiber end-face should be free of any contamination or defects, as shown below:

Common types of contamination and defects include the following:

Dirt Oil Pits & Chips Scratches

Simplex Ribbon


Contamination and Signal Performance

Fiber Contamination and Its Affect on Signal PerformanceCLEAN CONNECTION

Back Reflection = -67.5 dBTotal Loss = 0.250 dB

11

DIRTY CONNECTION

Back Reflection = -32.5 dBTotal Loss = 4.87 dB

33

Clean Connection vs. Dirty Connection

This OTDR trace illustrates a significant decrease in signal performance when dirty connectors are mated.


OTDRs


Reflection

Loss

Backscattered light

Transmitted lightFresnel Reflection

Reflective events on an OTDR


Mechanical Splice


Loss

Transmitted light

Non-Reflective Events


Fusion Splice


30 seconds

OTDR

OTDR Trace


WDM


[nm]

“C” Band

“L” Band

“O” Band

“E” Band

“S” Band

“U” Band

»C-Band - 1535nm to 1565nm

»L-Band - 1565nm to 1625nm

»U-Band - 1640nm to 1675 nm

»O-Band - 1260nm to 1310nm

»E-Band - 1360nm to 1460nm

»S-Band - 1460nm to 1530nm

1300 1400 1500 1600

Bands and Wavelengths


1310 nm

1550 nm

1625 nm

Fiber

Wavelength Division Multiplexing


1

0

1

0

0

1

0

1

0

1

0

0

1

0

Wave Division Multiplexing


Dense Wave Division Multiplexing

PRO: Virtually unlimited scalability of channels number and bandwidth

CON: higher equipment and maintenance cost

100Ghz spacing = 0.8 nm spacing

ITU Channels

C band – 100 channels

L band – 100 channels


Therefore ITU wavelengths




Coarse Wave Division Multiplexing

1271

1291

1311

1331

1351

1371

1391

1411

1431

1451

Most common

1471

1491

1511

1531

1551

1571

1591

1611

PRO: Wavelengths are 20 nm apart as a cost effective solution to DWDMCON: fiber issues prevalent and # of channels fixed

Wavelengths used:


CWDM System Overview

Coarse Wavelength division Multiplexing for metro network– Multiplexing a given number of channels: From 4 to 18 channels as per

ITU-T G.694.2– In a limited environment: Distance range (<80km). No need for amplifiers,

CD compensators…– Over a wide wavelength range (1271-1611nm)

• new fibers available (All Wave …). • First step, use of 1471-1611nm

– With a wide channel spacing (20nm)low cost components: Uncooled lasers, broad filters…


Wavelength Allocation

The nominal wavelength grid supporting CWDM systems has been defined by the ITU-T G.694.2 recommendation. It shows up a large wavelength range coverage (from 1271 to 1611nm) with a 20nm spacing.

O-Band E-Band S-Band C- Band L-Band

Water Peak

1271 12911311 133113511371

13911411

14311451

1471 1491 1511 1531 1551 15711591

1611

Wavelength (nm)

Attenuation (dB)


CWDM cost constraints

Central wavelength and drift tolerance– Lasers used for CWDM systems are directly modulated Distributed Feedback

(DFB) lasers with bit rates of up to 2.5 Gb/s. – Relaxed specifications for

• Central wavelength accuracy + wavelength drift over system lifetime. • Wide spacing of CWDM allows for a central wavelength to drift by as much as +/- 6.5 nm

MUX/DEMUX– CWDM transmission, with 20 nm channel spacing, allow using filters with reduced

technical constraints compare to DWDM, driving the cost dramatically down.


Channel/Wavelength turn-up (Alt. 2)

Optical channel verification according to the CWDM ITU-T G.694.2 grid over the full wavelength range.

Provide wavelength and power level measurements.

test

Mux

1551nm

1271nm

1291nm

1591nm

1611nm

Tx

Tx

Tx

Tx

Tx

test

test

Mux

1551nm

1271nm

1291nm

1591nm

1611nm

Tx

Tx

Tx

Tx

Tx

test

T-BERD 4000 OCC-4055 module used for

transmission wavelength verification

Handheld OCC-55 used for transmission

wavelength verification


CWDM Channel/Wavelength Provisioning

Test new wavelength route not yet in use Make sure wavelength goes through In-service test when other wavelengths already active

– OTDR test without disturbing current traffic– Reliable OTDR test taking other wavelength powers into account

CWDM OTDR 1551nm testing

Fiber Network

Mux

1511nm

1531nm

1551nm

1551nm

1471nm

1491nm

1591nm

1611nm

test-1551nm

traffic

traffic

traffic

traffic

traffic

test-1551nm

1311nm shot through Mux and Demux in presence of other wavelengths


Comparison between CWDM and DWDM


[nm]

“C” Band

“L” Band

“O” Band

“E” Band

“S” Band

“U” Band

»C-Band - 1535nm to 1565nm

»L-Band - 1565nm to 1625nm

»U-Band - 1640nm to 1675 nm

»O-Band - 1260nm to 1310nm

»E-Band - 1360nm to 1460nm

»S-Band - 1460nm to 1530nm

1300 1400 1500 1600

Bands and Wavelengths


Dense Wave Division Multiplexing

PRO: Virtually unlimited scalability of channels number and bandwidth

CON: higher equipment and maintenance cost


ITU Channels




Therefore ITU wavelengths




Dispersion


Different Polarization States = different speeds thru fiber The difference = Differential Group Delay (DGD) PMD = Mean value of various DGD’s

PMD – What is it ?

DGD

v1

v2

Fast

Slo

w

External stress !!

Values change constantly due to external stress (e.g., wind, temp, weight)

Compensation Unavailable


V1

V2

V1

V2

PMD


PMD as a function of Birefringence

Stresses and Strains on the fiber changes the shape of the cladding and core. As the stresses change at various point throughout the fiber link, coupled with the polarization states constantly spinning, makes pin pointing PMD and removing the “bad” section a game of chance.

Perfect FiberStrained Fiber

Fiber Strain Causes


Evolution of Dispersion testing

Rate PMD Max CD Coef Max at

1550 nm

Max Distance in before DCMs*

OC - 12 160 ps 301056 ps/nm*km 10625 miles

OC-48 40 ps 18816 ps/nm*km 576 miles

OC-192 10 ps 1176 ps/nm*km 36 miles

10 Gig E 5.0 ps 738 ps/nm*km 25 miles

OC-768 2.5 ps 64 ps/nm*km 2.25 miles

* Distances are for SMF-28 fiber. Amount of compensation varies dramatically with different fiber types introduced into a network.


Dispersion Testing Timeline

1980 – 1997 - PMD and CD testing not widely performed outside of the lab

1985 – 1989 - PMD purposely added to fiber to try to compensate for CD

1997 - OC-48 rollout begins and PMD testing and CD testing begins in different areas

1995 - 2006 – companies consolidate with other companies with different fiber types.

2002 – OC-192 rollout begins and PMD and CD testing performed more widespread.

2005 – 10 GigE rolled out over SONET. PMD and CD testing continues on links some mandated by SLAs

2009 – OC-768 rollout begins.


Chromatic Dispersion – What is it ?

Pulse spreading

Different wavelengths = different speeds thru fiber Value doesn’t change (ps/nm.km) Can be compensated using DCMsOver compensating just as dangerous as under compensating

InputPulse

Output Pulse


Attenuation Profile (AP)

Characterizes fiber for Wavelength Dependent Loss

Indicates where engineers efficiently place Optical Amplifiers adding to cost savings

Allows for intelligent planning of CWDM wavelengths


Questions

John Swienton

Office:413-525-1379

Cell: 413-231-2077

[email protected]

Fiber Optics John Swienton Fiber Geek - JDSU [email protected].

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Transcript of Fiber Optics John Swienton Fiber Geek - JDSU [email protected].