DWDM Basic Presentation

1 © Nokia 2014

DWDM Basics

This document provides a Tutorial/Course on DWDM fundamental and their applications.

By RSO Tx

23-09-2014

For Internal use only

2 © Nokia 2014

Brief Description

In this course, participants will acquire an overview of the technology

used in Dense Wavelength Division Multiplexing including Optical

Technology principles. Participants will learn the advantages of DWDM

over traditional optical transport technologies such as SDH. An overview

of the building blocks used in a DWDM network followed of the basic

functions performed by the various building blocks.


3 © Nokia 2014

Contents Optical Basics : Sources of Attenuation, Dispersion Effects,

Chromatic & Polarization Mode Dispersion, Effects of Nonlinear Optics

Concepts of WDM, an Introduction, Why do we need WDM?

CWDM and DWDM Links

Types of Optical Network Elements

ITU-T Channel Grid

Building Blocks of Optical Network Elements :

Optical Multiplexers and Demultiplexers ,

Optical Amplifiers

Light Sources and Photo Detectors

DWDM Use Cases


4 © Nokia 2014

Optical Fiber

1.Single-Mode Fiber (SMF)

2.Properties of Fiber

3.Classifications of Single Mode Fiber

4.Nonlinear Effects of Single Mode Fiber

5 © Nokia 2014

Structure of Single-Mode Fiber and Refractive Index Profile

Structure of a fiber

d

n2

n1

d

n2

n1

Refractive index profile coating

n 2 cladding

n 2 cladding

coating

core n 1 d 1 d2


6 © Nokia 2014

The Optical Spectrum


Wavelength (m) 10

-12 10

-9 10

-6 10

-3 10

0 10

2

(1 pm) (1 nm) (1 μm) (1 mm) (1 m) (100 m)

1016

1014

1012

1010

108 10

6

(250 THz) (1 THz) (1 GHz)

1018

1020

Frequency (Hz)

Cosmic

Radiation γ Radiation UV Radiation

Visible Light

IR Radiation Communications Radiation

X-ray

Radiation TV VHF SW Microwave,

Radar

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 μm

780 670 850 1300 1550 1625 nm

Visible Light

Fiber Transmission Wavelength Range

λ = Wavelength f = Frequency c = 300 000 km/s

c = λ x f

7 © Nokia 2014

Fiber Attenuation

Attenuation in optical fiber is mainly determined by three types of

loss: absorption loss, scattering loss and bend loss.

Attenuation coefficient （unit:dB/km）

λ(nm) 1550 1310

OH- ion Absorption

Atte

nu

atio

n (d

B)

C_band L_band


8 © Nokia 2014

Dispersion

9 © Nokia 2014

Dispersion in Single Mode Fiber (SMF)

• Dispersion in fiber refers to a physical phenomenon of signal distortion caused

when various modes carrying signal energy or different frequencies of the signal

have different group velocity and disperse from each other during propagation.

• Dispersion in SMF is classified into chromatic dispersion and polarization mode

dispersion (PMD)


10 © Nokia 2014

Chromatic Dispersion

Input laser is not monochromatic,

it is composed of many

wavelength or colour.

The different wavelengths arrive

at different times to BROAD,

separated, or DISPERSED output

pulse.

The chromatic dispersion in the

fiber causes different wavelengths

to travel at different speeds, and

propagation delay.

Input laser

Optical receiver

L

DATA IN DATA OUT

11 © Nokia 2014

Chromatic Dispersion

Dis

pers

ion

(p

s/n

m·k

m)

G.653

λ(nm) 1550 1310

G.652 fiber

G.655

17

Generally, two kinds of dispersion exist in single mode optical fiber, they are

material dispersion and waveguide dispersion.

Dispersion coefficient（unit：ps/nm∙km）


G.655

12 © Nokia 2014

Polarization Mode Dispersion－PMD

Detector

power

Signal response

Fiber

profile

Ellipse fiber core

Slow in propagation

Fast in propagation

Delay time


13 © Nokia 2014

λ3 λ1 λ3 λ1 λ3 λ3λ1 λ1

T T+ΔT

Inter-symbol Interference

Broaden pulse caused by dispersion will bring the adjacent consecutive pulses to overlap.


14 © Nokia 2014

Mode Field Diameter and Effective Area

• Mode field diameter（MFD）describes the concentrate level of

optical energy in the single mode fiber.

Fiber core

MFD


15 © Nokia 2014

Dis

pers

ion

(p

s/n

m·k

m)

G.653

λ(nm) 1550 1310

G.652 fiber G.655

OH- ion Absorption

17

Att

enuation

(d

B/k

m)

C_band L_band

Types of Optical Fiber

G.654fiber


16 © Nokia 2014

Nonlinear Effects in Single Mode Fiber

• Stimulated Nonelasticity Scattering

- Stimulated Brillouin Scattering(SBS)

- Stimulated Raman Scattering(SRS)

• Kerr effect

- Self-phase Modulation(SPM)

- Cross-phase Modulation(XPM)

• Four-wave Mixing(FWM) For Internal use only

17 © Nokia 2014

Stimulated Nonelasticity Scattering

• Stimulated Raman Scattering(SRS)

- Limiting the injection power, threshold

power is100mW.

• Stimulated Brillouin Scattering(SBS)

- Limiting the optical power of single

wavelength，threshold power is smaller for

spectrum line lasers.


19 © Nokia 2014

Kerr Effect

• Self-phase Modulation (SPM)

- Broaden the signal's spectrum,

- the influence of dispersion becoming bigger.

• Cross-phase Modulation

- Limiting the input optical power and the

wavelength spacing.


20 © Nokia 2014

Four-Wave Mixing

• Four-wave mixing (FWM) occurs in the case that two or three light waves with

different wavelength interact and cause new light waves at other wavelengths.

1 2

f 113

F 123,213

F112 F223

F 132,312

F221

F231,F321

F332 F331

F F F3

Uneven and relatively large channel spacing can reduce FWM.

21 © Nokia 2014

How to increase network capacity？

Solution of capacity expansion

Add the Mux

Add fiber &

equipment

TDM

STM-16→ STM-

64

WDM

Economical,


Implication-Time & cost Implication-Cost & Complication

Benefit - Mature and Quick

22 © Nokia 2014

Wavelength Division Multiplexing

The ability to use different wavelengths, in a single fiber, to combine and to split them.

Single fiber unidirectional transmission with various payloads

SDH signal

IP package

ATM cells

1

2

┋

1 2 n

┉

n


23 © Nokia 2014

Why WDM ?

a) Overcome fiber exhaust / lack of fiber availability

problems (better utilization of available fiber)

d) Cost effective transmission

e) No O-E-O conversion delays

f) Wave length leasing instead of Bandwidth leasing

b) Space and Power savings at intermediate stations

c) Easier capacity expansion


24 © Nokia 2014

…Why WDM ?

Traditional Network with Repeaters, no WDM

LTE LTE LTE LTE

LTE LTE LTE LTE

75% fewer fibers WDM Network with Repeaters

LTE LTE LTE LTE

LTE LTE LTE LTE

75% less equipment WDM Network with Optical Amplifiers

LTE LTE LTE LTE

LTE LTE LTE LTE


25 © Nokia 2014

WDM ….. a Business Case.

TERM

TERM

TERM

Conventional TDM Transmission — 10 Gbps

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR TERM

40km

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR TERM

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR TERM

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR

1310

RPTR TERM

120 km

STM-16

OA OA OA OA

120 km 120 km STM-16

STM-16 STM-16

STM-16 STM-16

STM-16 STM-16

DWDM Transmission — 10 Gbps

1 Fiber Pair

4 Optical Amplifiers

TERM

4 Fibers Pairs

32 Regenerators

40km 40km 40km 40km 40km 40km 40km 40km


26 © Nokia 2014

WDM Link System Structure

• The overall structure of the WDM system of N-path wavelength:

- Optical Transponder Unit (OTU)

- Optical Multiplexer Unit / Optical De-multiplexer Unit (OMU/ODU)

- Optical Amplifier (OA)

- Supervisory Channel (OSC/ESC)

OTU

OTU

OTU

O

M

U/

O

A

O

A/

O

D

U

OTU

OTU

OTU

OSC OSC OSC

OLA


27 © Nokia 2014

Transmission Modes

Single fiber bidirectional transmission

M

4

0

M

4

0

MUX/DMUX DMUX/MUX

O

T

U

O

T

U


28 © Nokia 2014

DWDM Basics - multiplexing of optical wavelengths


29 © Nokia 2014

CWDM Vs DWDM

CWDM:

Coarse Wavelength Division Multiplex

DWDM:

Dense Wavelength Division Multiplex

Extended C band 192chs, 25GHz spacing

196.05THz 192.125THz

C band 160chs

192.05THz

Extended

32chs

191.275THz

ITU-T G.694.1


30 © Nokia 2014

CWDM Vs DWDM

Coarse Wavelength Division Multiplexing:

1. Short-range communications

2. Coarse wavelength – (2 to16 )

3. Uses wide-range frequencies

4. Wavelengths spread far apart (20 nm)

5. Wavelength drift is possible

6. Breaks the spectrum into big chunks

7. Light signal isn't amplified (No OA/OLA)

Dense Wavelength Division Multiplexing

1. Long-haul transmissions (with BA/OLA/PA)

2. Dense Wavelengths ( 32, 40,80, 160, 192)

3. Narrow frequencies

4. Tightly packed wavelengths (25Ghz Spacing)

5. Precision lasers required to keep on target

6. Dices the spectrum into small pieces

7. Signal amplification maybe used (with BA/OLA/PA)


31 © Nokia 2014

Infrared Spectrum

O Band E Band S Band C Band L Band

1260

-1360 n

m

1460

-1530 n

m

1530

-1565 n

m

CWDM CWDM Future

DWDM

CWDM/

DWDM


CWDM/

DWDM

32 © Nokia 2014

ITU-T Channel Grid


33 © Nokia 2014

Wavelength Allocation for DWDM

(ITU-T G.692)

C Band (1530 – 1562nm)

L Band (1574 – 1608 nm)

The channel central frequencies are allocated in equal

frequency spacing of 100 GHz or 0.8 nm


34 © Nokia 2014

(nm)

1532.6

8

1533.4

7

1534.2

5

1535.0

4

1535.8

2

1536.6

1

1537.4

0

1538.1

9

1538.9

8

1539.7

7

1540.5

6

1541.3

5

1542.1

4

1542.9

4

1543.7

3

1544.5

3

1545.3

2

1546.9

2

1547.7

2

1548.5

2

1549.3

2

1550.1

2

1550.9

2

1551.7

2

1552.5

2

1553.3

3

1554.1

3

1554.9

4

1555.7

5

1556.5

6

1557.3

6

1558.1

7

1558.9

8

1559.7

9

1560.6

1

1561.4

2

1562.2

3

1530.3

3

1531.1

2

1531.9

0

(THz)

195.7

195.6

195.5

195.4

195.3

195.2

195.1

195.0

194.9

194.8

194.7

194.6

194.5

194.3

194.2

194.1

194.0

193.8

193.7

193.6

193.5

193.4

193.3

193.2

193.1

193.0

192.9

192.8

192.7

192.6

192.5

192.4

192.3

192.2

192.1

192.0

191.9

196.0

195.9

195.8

C

37

C36

C35

C34

C33

C32

C31

C30

C29

C28

C27

C26

C25

C24

C23

C22

C21

C20

C19

C1

8

C17

C16

C15

C14

C1

3

C12

C11

C10

C09

C0

8

C07

C06

C05

C04

C03

C02

C0

1

C4

0

C39

C38

Carrier

wavelength

Carrier

frequency

Channel

number

Note 1: Optical carriers are allocated on ITU-T 100 GHz (0.1 THz) grid in G.692

Wavelength Allocation in C Band


35 © Nokia 2014

(nm)

1577.0

3

1577.8

6

1578.6

9

1579.5

2

1580.3

5

1581.1

8

1582.0

2

1582.8

5

1583.6

9

1584.5

3

1585.3

6

1586.2

0

1587.0

4

1587.8

8

1588.7

3

1589.5

7

1590.4

1

1592.1

0

1592.9

5

1593.7

9

1594.6

4

1595.4

9

1596.3

4

1597.1

9

1598.0

4

1598.8

9

1599.7

5

1600.6

0

1601.4

6

1602.3

1

1603.1

7

1604.0

3

1604.8

8

1605.7

4

1606.6

0

1607.4

7

1608.3

3

1574.5

4

1575.3

7

1576.2

0

(THz)

190.1

190.0

189.9

189.8

189.7

189.6

189.5

189.4

189.3

189.2

189.1

189.0

188.9

188.8

188.7

188.6

188.5

188.3

188.2

188.1

188.0

187.9

187.8

187.7

187.6

187.5

187.4

187.3

187.2

187.1

187.0

186.9

186.8

186.7

186.6

186.5

186.4

190.4

190.3

190.2

L

04

L

05

L

06

L

07

L

08

L09

L

10

L

11

L

12

L

13

L

14

L

15

L

16

L

17

L

18

L

19

L

20

L21

L

22

L

23

L

24

L

25

L

26

L

27

L

28

L

29

L

30

L

31

L

32

L33

L

34

L

35

L

36

L

37

L

38

L

39

L

40

L01

L

02

L

03

Carrier

wavelength

Carrier

frequency

Channel

number

Note 1: Optical carriers are allocated on ITU-T 100 GHz (0.1 THz) grid in G.692

Wavelength Allocation in L Band


36 © Nokia 2014

WDM Link System Structure

• The overall structure of the WDM system of N-path wavelength:

- Optical Transponder Unit (OTU)

- Optical Multiplexer Unit / Optical De-multiplexer Unit (OMU/ODU)

- Optical Amplifier (OA)

- Supervisory Channel (OSC/ESC)

OTU

OTU

OTU

O

M

U/

O

A

O

A/

O

D

U

OTU

OTU

OTU

OSC OSC OSC

OLA


37 © Nokia 2014

Main functional blocks for building DWDM networks


38 © Nokia 2014

Main functional Blocks for building DWDM networks


39 © Nokia 2014

DWDM Basics - building pure optical, transparent, fully-meshed DWDM networks


41 © Nokia 2014

Board Category /Type

Unit Category Board Name

Optical Transponder Unit

LWF(S), LRF(S), LBE(S), ETMX(S),TMX(S), TMR(S), LWC1,

TRC1, LWM, LWMR, LWX, LWXR, LQS, LDG, FDG,LOM(S),

LOG(S), LQG, L4G, EGS8, LAM, LBF, AS8, AP8, FCE, EC8,

LAM,TBE,LW40(LSX,LWXS,LQM,NS2/3,ND2,NQ2-OSN6800)

Multiplexer and Demultiplexer M40, V40, D40, FIU, EFIU,DWC(D40V,ITL IN OSN6800)

Add and Drop Multiplexing Unit MR4, MR2, SBM2, SBM1, MB2,MB4,DWC,WSD9, RMU9,

WSM9, WSMD4

Optical Amplifier Unit OAU, OBU, OPU,RPC

Optical Supervisory Unit & SCC SC1, SC2, ST1,ST2,SCC

Optical Protection Unit OLP, SCS, DCP,OWSP

Auxiliary Unit VOA, VA4, MCA, PMU


42 © Nokia 2014

OEO OEO TX

RX

TX

RX

MU

X/D

EM

UX

MU

X/D

EM

UX

OA OADM OA

TX

RX

TX

RX

Client

TX RX

Client

Transponder interface

To Client Devices

Components of DWDM Systems


43 © Nokia 2014

Transponders

A transponder is a wavelength converter.

They are optical-electrical-optical (OEO) in nature.

In optical fibers the data is carried at 850nm, 1310nm or 1550nm.

WDM systems need to multiplex different ITU-compliant wavelengths

together.

Therefore, these signals must all be converted to a particular wavelength that

is suitable for either a CWDM or DWDM system.


44 © Nokia 2014

TRANSPONDER

Non-ITU-T

Complaint Wavelength

850, 1310, 1550

OPTICAL FIBER

O-E-O

Wavelength

Conversion TX

RX

ITU-T

Complaint Wavelength

15xx.xx nm

Transponder Block Diagram

Transponder

850/1310 15xx


45 © Nokia 2014

Optical Transponder Unit in OSN8800


46 © Nokia 2014

Optical Multiplexers and Demultiplexers

Optical multiplexers combine multiple wavelengths from several sources

for transmission across a single optical fiber.

Multiplexed optical signals are collectively referred to as the composite

signals.

Optical Demultiplexers separate different wavelengths from a composite

signal received from a single optical fiber.

Demultiplexed optical signals are then passed to optical receivers.


47 © Nokia 2014

Optical Multiplexer / De-multiplexers.

Optical Multiplexer

1

2

3

1...n

Optical De-multiplexer

2

3

1...n

1


48 © Nokia 2014

Optical Multiplexer (OMUX)

Transmit Amplifier (TXA)

OMUX

Aggregate Signal over n-

channels with wavelengths

ranging from λ1 to λn

Channel

#1

#2 #3

#(n-1) #(n-2)

#n

Wavelength

λ1

λ2 λ3

λ(n-1) λ(n-2)

λn λ1 λ2 λn λ(n-1)

100 GHz

Cli

ent


49 © Nokia 2014

Receive Amplifier (RXA)

ODMUX

Aggregate Signal over n-

channels with wavelengths

ranging from λ1 to λn.

Channel

#1

#2 #3

#(n-1) #(n-2)

#n

Wavelength

λ1

λ2 λ3

λ(n-1) λ(n-2)

λn λ1 λ2 λn λ(n-1)

100 GHz

Cli

ent

Optical Demultiplexer (ODMUX)


50 © Nokia 2014

Demultiplexing


51 © Nokia 2014

Reflection Grating Filters

Reflect a single wavelength

and transmit the rest


52 © Nokia 2014

Diffraction Gratings

Each wavelength is diffracted at a different angle, using a lens these

wavelengths can be focused onto individual fibers.


53 © Nokia 2014

Arrayed Waveguide Grating


54 © Nokia 2014

M40/M40V

AWG

M40V OUT

MON

M01 ……… M40

splitter

- 40-channel multiplexing unit without/with VOA

- Adjusts the optical power of each signal after

demultiplexing (M40V).

- C-Even and C-Odd Band

- Online Performance Monitoring(10dB)

M40

M40

STATACTPROGSRV

CLASS 1

LASER

PRODUCT

M01M02M03M04M05M06M07M08M09M10

M11M12M13M14M15M16M17M18M19M20

M21M22M23M24M25M26M27M28M29M30

M31M32M33M34M35M36M37M38M39M40

196.00195.90195.80195.70195.60195.50195.40195.30195.20195.10

195.00194.90194.80194.70194.60194.50

194.20194.10

194.40194.30

194.00193.90193.80193.70193.60193.50

193.20193.10

193.40193.30

193.00192.90192.80192.70192.60192.50

192.20192.10

192.40192.30

M15

M16

M17

M18

M19

M20

M21

M22

M23

M24

M13

M25

M26

M14

M01

M02

M03

M04

M05

M06

M07

M08

M09

M10

MO

NM

11

M12

OU

T

M29

M30

M31

M32

M33

M34

M35

M36

M37

M38

M28

M39

M40

M27


55 © Nokia 2014

D40/D40V

- 40-channel demultiplexing unit without/with VOA

- Adjusts the optical power of each signal after

demultiplexing (D40V).

- C-Even and C-Odd Band

- Online Performance Monitoring(10dB)

AWG

D40V IN

MON

D01 ……… D40

splitter

D40

D40

STATACTPROGSRV

CLASS 1

LASER

PRODUCT

D01D02D03D04D05D06D07D08D09D10

D11D12D13D14D15D16D17D18D19D20

D21D22D23D24D25D26D27D28D29D30

D31D32D33D34D35D36D37D38D39D40

196.00195.90195.80195.70195.60195.50195.40195.30195.20195.10

195.00194.90194.80194.70194.60194.50

194.20194.10

194.40194.30

194.00193.90193.80193.70193.60193.50

193.20193.10

193.40193.30

193.00192.90192.80192.70192.60192.50

192.20192.10

192.40192.30

D15

D16

D17

D18

D19

D20

D21

D22

D23

D24

D13

D25

D26

D14

D01

D02

D03

D04

D05

D06

D07

D08

D09

D10

MO

ND

11

D12

IN

D29

D30

D31

D32

D33

D34

D35

D36

D37

D38

D28

D39

D40

D27


56 © Nokia 2014

Optical MUX & DEMUX Unit

• ITL

- Multiplexes and demultiplexes C_ODD and C_EVEN signals

- Online performance monitoring (10dB)

IN

OUT

C- odd Interleaver

Coupler /

Interleaver

C-even

C- odd

C-even

MON

Splitter

TO

TE

RO

RE


57 © Nokia 2014

OADM Signals

The “drop” signal is filtered out of the composite signal

The “add” signal is coupled to the composite signal

Pass through signals are neither dropped from nor

added to the OADM

Each signal path has an insertion loss in dB


58 © Nokia 2014

DWDM Fiber

Drop Path Add Path

Original

Composite

Signal

Pass Through Path New

Composite

Signal

Channel-1

Drop Channel-1

Add

OADM Block Diagram


59 © Nokia 2014

Optical Add Drop Multiplexers (OADM)

Wavelength Selection devices.

Used to drop and add one or more optical

channels from a composite signal

into a DWDM fiber.

Three signal paths

• Drop

• Add

• Pass through

Optical Add Drop Multiplexer

(OADM)

1

2

3


60 © Nokia 2014

Isolator and Circulator

61 © Nokia 2014

Page 61

Circulator

2

Fiber grating

62 © Nokia 2014

OADM Unit

Board

category

Board

name Board description

Fix OADM Unit MR8V 8-channel optical add/drop multiplexing unit with VOA

Reconfigurable

OADM Unit

WSM9 9-port wavelength selective switching multiplexing board

WSD9 9-port wavelength selective switching demultiplexing board

RDU9 9-port ROADM demultiplexing board

RMU9 9-Port ROADM multiplexing board

WSMD4 4-Port Wavelength Selective Switching Multiplexer and Demultiplexer

Board


63 © Nokia 2014

OADM Unit

• MR8V

- 8-channel optical add/drop multiplexing unit with VOA

- Realizes the adding/dropping and multiplexing of eight signals and

adjusts the input optical power of each channel.

OADM optical

module

MI OUT

A1 A8

D1 D8

IN MO

.....

.....


64 © Nokia 2014

ROADM Unit

• WSD9

- Configured any wavelengths (80λs) to any interfaces (9D)

- Adjust the optical power of each channel

- Online optical performance monitoring

- Supports C_Even and C_Odd Band

…

…

…

IN

DM1

DM8

EXPO

MONI

MONO

WSD9

WSD9

LASERRADIATION

DO NOT VIEW DIRECTLY

WITH OPTICAL

INSTRUMENTS

CLASS 1M LASER

PRODUCT

STATACTPROGSRV

DM

1D

M2

DM

3D

M4

EX

PO

IND

M5

DM

6M

ON

OM

ON

ID

M7

DM

8


65 © Nokia 2014

OADM Unit

• RMU9

- Adds 8 single-channel signal or multi-channel signals to the main path,

realizes the dynamic input of eight channel signals using tunable OTUs.

Coupler

EXP

I

OUT

ROA

TOA

AM

1

MONO

MONI

AM

8

VO

A

Coupler

RMU9

RMU9

STATACTPROGSRV

CLASS 1

LASER

PRODUCT

MO

NO

MO

NI

OU

TE

XP

ITO

AR

OA

AM

1A

M2

AM

3A

M4

AM

5A

M6

AM

7A

M8


66 © Nokia 2014

OADM Unit

• WSMD4

- 4-Port Wavelength Selective Switching MUX & DEMUX

- Adjust the optical power of any add wavelengths

- Online optical performance monitoring

- C-even & C-odd

MONO

MONI

IN

…

…

…

OUT AM1

AM2

AM4

RDU

DM1 DM2 DM3 DM4

…

WSMD4

WSMD4

STATACTPROGSRV

DM

1A

M1

DM

2A

M2

OU

TIN

DM

3A

M3

MO

NO

MO

NI

DM

4A

M4

LASERRADIATION


WITH OPTICAL

INSTRUMENTS

CLASS 1M LASER

PRODUCT


67 © Nokia 2014

Optical Amplifier

• The optical power is increased by optical

amplifier.

Amplified optical signal Input optical signal OA


68 © Nokia 2014

Common Parameters of Optical Amplifier

• Gain

• Noise Figure

• Gain bandwidth

• Saturated output power

0

10

20

λ

Gain

(dB

)

30 3dB

λb λa

Pin

Gain

(dB

)

3dB

PT P

out (d

Bm

)

PS

Pout

Gain


69 © Nokia 2014

Types of Optical Amplifier

• Erbium Doped Fiber Amplifier (EDFA)

• Raman Fiber Amplifier (RFA)

• Semiconductor Optical Amplifier (SOA)


70 © Nokia 2014

EDFA Energy Level Diagram

The stimulated radiation and ASE of Er3+ ions in the EDF

ASE accumulation is resource of noise

Pump E2 metastable state

E3 excited state

1550nm

E1 ground state

1550nm

Decay

light

signal light signal light

71 © Nokia 2014

Advantages and Disadvantages of EDFA

Major advantages of EDFA:

• Its operating wavelength is consistent with the minimum loss window of

the SMF.

• High coupling efficiency, Active Medium is in fiber.

• High energy conversion efficiency.

• High gain, low noise figure, large output power and low cross-talk.

• Stable gain characteristics.

Major disadvantages of EDFA:

The gain wavelength range is fixed.

Gain bandwidth unflatness.

Optical surge problem. For Internal use only

72 © Nokia 2014

The Operating principle of Raman Fiber Amplifier

• Stimulated Raman Scattering(SRS)

Pump

Gain

30nm

70~100nm


73 © Nokia 2014

Characteristics of Raman Fiber Amplifier

• Its gain wavelength is determined by the pump wavelength.

• The gain medium is the transmission fiber itself.

• Low noise. PUMP1 PUMP3

70~100nm 30nm

GAIN PUMP2

EDFA

Span 1

Raman Pump

transmitting Receiving

EDFA

Span k

Raman Pump


74 © Nokia 2014

Classifications of Raman Fiber Amplifier

• Discrete Raman Fiber Amplifier

• Distributed Raman Fiber Amplifier


75 © Nokia 2014

RFAs and EDFAs

76 © Nokia 2014

Advantages of RFA

Advantages:

• Gain wavelength is determined by the pumping light wavelength ;

• Simple structure of amplifier;

• Nonlinear effects can be reduced;

• Low noise;

PUMP1 PUMP3

70~100nm 30nm

GAIN PUMP2


77 © Nokia 2014

Disadvantages of RFA

Disadvantages: • High pump power, low efficiency and high cost;

• Instantaneous gain, adopting backward pump fashion;

• Optical components and optical fiber undertake high optical power;

• Characteristics of gain online are not consistent.


78 © Nokia 2014

Advantages and Drawbacks of SOAs

Advantages: • Operating at the 1300nm and 1550nm wavelengths-even simultaneously.

• Wide bandwidth(up to 100nm has been achieved)

• Easy to integrate, along with other semiconductor and photonic devices,

into one monolithic chip called opto-electronic integrated circuit (OEIC)

Drawbacks:

Relatively high crosstalk, polarization

sensitivity

High temperature sensitivity; For Internal use only

79 © Nokia 2014

Comparison of Three Types of Amplifiers

Type EDFA SOA Raman

Maturity maturity Not maturity maturity

Gain high normal normal

Bandwidth wider wide Very wide

Coupling

efficiency

high low high

Cost moderate high high

80 © Nokia 2014

Optical Amplifying Unit

• OAU1

- Amplifies 80 channels of C-band optical signals

- Continuously adjusts the gain

- Online performance monitoring

- Gain locking function

- Transient control function

OAU1

OAU1

LASERRADIATION


WITH OPTICAL

INSTRUMENTS

CLASS 1M LASER

PRODUCT

STATACTPROGSRV

TDC

PD

CO

UT

INM

ON

Type Range Type Range

OAU101 20~31dB OAU103 24~36dB

OAU102 20~31dB OAU105 23~34dB


81 © Nokia 2014


• OAU1

- Functional modules and signal flow

IN OUT

MON

RDC

1 2 3 4 5

TDC

VOA

OAU

Splitter PA BA

DCM


82 © Nokia 2014


• OBU1

- Amplifies 80 channels of C-band optical signals

- Online performance monitoring

- Gain locking function

- Transient control function

OBU1

OBU1

MONOUT

IN

STATACTPROGSRV

LASERRADIATION


WITH OPTICAL

INSTRUMENTS

CLASS 1M LASER

PRODUCT

IN OUT

MON

OBU1 Splitter

BA


83 © Nokia 2014

Light Sources and Photo Detectors

• Light sources

• Laser modulation modes

• Types and characteristics of photo

detectors

84 © Nokia 2014

Types and Characteristics of Light Source

• LED

• FP-LD (MLM)

• DFB-LD (SLM)

Low output power,

Poor beam focus,

Wide spectrum, low bit rate,

Inexpensive,

Suit for short distance communications

High output power

Good beam focus

Narrow spectrum, high bit rate

expensive

Suit for long distance For Internal use only

85 © Nokia 2014

Modulation Techniques

• Direct modulation (internal modulation)；

• Indirect modulation (external modulation)：

- Electro-Absorption modulation

- Mach-Zehnder modulation


86 © Nokia 2014

Direct Modulation

Direct modulation is: Output laser is controlled by input

current

Advantages: simple structure,low loss and low cost

Disadvantages: modulation chirp

transmission distance ≤ 100km

transmission rate ≤ 2.5Gbit/s

LD

Current Laser

87 © Nokia 2014

What is chirp?

Chirp(as in bird chirping) is the deviation of laser frequency

from its radiation-center frequency.

positive chirp negative chirp

no chirp

fore edge back edge

88 © Nokia 2014

Electro-Absorption Modulator

E-A modulation modulates the laser indirectly and adding an external

modulator in its output path to modulate the light intensity.

• Support long haul transmission (2.5Gb/s >600km)

• Less chirp

• High reliability

• Complex technology

LD EA


89 © Nokia 2014

Mach-Zehnder Modulator

Advantages:

• chirp can be almost zero

• suit for long transmission distance Disadvantages:

• Expensive

LD

90 © Nokia 2014

Comparision of Modulations

Types Direct Modulator EA Modulator M-Z Modulator

Max.dispersion

tollerance

(ps/nm)

1200~4000 7200~12800 >12800

Cost moderate expensive Very expensive

Wavelength Stability good better best

For STM-16 Signal

91 © Nokia 2014

Photo Detector

• The function of photoelectric detector is to convert the received optical signal to corresponding

electric signal.

- Positive Intrinsic Negative（PIN）

- Avalanche Photo Diode（APD）

• Dynamic ranges：

- The difference of overload power and receiving sensitivity is called dynamic ranges,

generally about 20dB.

Types Spectrum response Overload Power Optical Sensitivity

PIN 1100～1600nm 0dBm -20dBm

APD 1000～1600nm -9dBm -28dBm


92 © Nokia 2014

Optical Supervisory Channel Unit

• SC2

- Realizes the processing of two supervisory

channels in opposite directions

- Operating Wavelength: 1510nm

- Supports a maximum of 48 dB transmission

- Supports order-wire function


93 © Nokia 2014

Other Units

Board category Board

name Board description

Occupied

slots

Optical protection unit

DCP 2-channel optical path Protection unit 1

OLP Optical line protection unit 1

SCS Sync optical channel separator unit 1

Spectrum analyzer unit

MCA4 4-channel spectrum analyzer unit 2

MCA8 8-channel spectrum analyzer unit 2

WMU wavelength monitored unit 1

Variable optical

attenuator unit

VA1 1-channel variable optical attenuator unit 1

VA4 4-channel variable optical attenuator unit 1

Optical Power and

Dispersion

Equalizing Unit

DCU dispersion compensation unit 1

TDC single-channel tunable-dispersion compensation board 1

GFU gain flatness unit 1


94 © Nokia 2014

Other Units

• OLP (Optical Line Protection Unit)

- Supports optical line protection

- Supports intra-OTU 1+1 protection

- Supports client-side 1+1 protection

OLP

OLP

STATACTPROGSRV

LASERRADIATION


WITH OPTICAL

INSTRUMENTS

CLASS 1M LASER

PRODUCT

TO1RI1

TO2RI2

ROTI

RO1

TI1

RI11 RI12

TO11 TO12

Optical splitter

Optical Switch


95 © Nokia 2014

Other Units

• SCS (Sync optical Channel Separator)

- Supports client-side 1+1 protection

- Supports BPS protection

SCS

SCS

CLASS 1

LASER

PRODUCT

TO11TO12

RI12TO21

RI21TO22

RI22RO1

TI1RO2

TI2RI11

RO1

TI1

RI11 RI12

TO11 TO12

TI2

RO2 RI21 RI22

TO21 TO22

Optical splitter

Optical coupler

Optical splitter

Optical coupler


96 © Nokia 2014

Other Units

• MCA4

- Functions and Features

• Supports the following detection functions

and reporting

- Optical power of the channel

- Central wavelength

- Optical signal-to-noise ratio

- Number of wavelengths in the main optical path

• Used in APE function with other boards

MCA4

MCA4

STATACTPROGSRV

IN1

IN2

IN3

IN4


97 © Nokia 2014

Other Units

• WMU - Realizes the wavelength monitoring in the system with

wavelengths at 50 GHz channel spacing.

WMU

WMU

STATACTPROGSRV

IN1

IN2

I

T

L

OBU1

OTU M

4

0

M40V

OTU M M40V

WMU

F

I

U

C_EVEN

C_ODD


98 © Nokia 2014

DWDM Use Cases - High-Capacity Long-Distance Optical Backbone

traditional backbone

SDH over optical fiber

up to 10Gb/s transmission speed

single wavelength per fiber

congested links

capacity and distance limitations

DWDM backbone

SDH over DWDM over optical fiber

up to 80 x up to 40G per optical fiber

no congestions anymore, free capacity for any new

traffic, even for re-selling

full optical mesh for scalability and

flexibility (any new service from any to any location)

A

B C

D

E

F

A

B C

D

E

F

10G SDH

1

congested

< 40

< 40G/

TDM/packet/any serv.

< 3.2 Tb/s

free capacity


99 © Nokia 2014

DWDM Use Cases - IP/MPLS Core Router Interconnection

without DWDM

expensive SDH router interfaces (2.5G -

still ok, 10G - prohibitive)

long distances between core routers

cannot be bridged easily

40G interfaces impossible to transport

over distances by standard methods

with DWDM

use of low-cost, short-range Ethernet router I/f

ability to transport upcoming 40G traffic over

long distance

cost savings with transponder-less 40G IP-over-

DWDM solution

DWDM links can be additionally used for other

traffic and services

SDH 2.5G

SDH

2.5G

SDH

10G SDH

10G

40G not possible

D

B C

A

D

B C

A

SDH 2.5G

SDH

2.5G

10GE

on

10GE

on

40G on

transponderless

interworking w/

Juniper possible


100

© Nokia 2014

DWDM Use Cases - Metro Multi-Service Aggregation

data

X

Access Edge Metro

data

Access Edge Metro

A

B

traditional Metro

mobile/fixed broadband multi-service environment,

business services

multi-service aggregation by NG-SDH and Carrier Ethernet

booming traffic, optical fiber shortage

no possibility to offer data services

WDM-empowered Metro

Case A : multi-service aggregation by NG-SDH/Carrier

Ethernet plus Metro WDM for boosting fiber capacity

Case B : multi-service transport by native Metro WDM

(1 service per , transparent, point-to-point)

data services possible


104

© Nokia 2014

Extra Pictures


105

© Nokia 2014

Extra Pictures


106

© Nokia 2014

Extra Pictures


107

© Nokia 2014

Extra Pictures


108

© Nokia 2014

Colors and fonts Use sentence case for slide titles

Core and background colors

18 65 145

0 201 255

104 113 122

168 187 192

216 217 218

R G B

We use blue and white predominantly, and selectively call out key points in light blue. If necessary, we use our palette of grays to help highlight supporting information.

Document fonts Nokia Pure is our business font and should be used as a priority.

If you do not have this font installed, Arial is the

acceptable alternative.

the presentation title should be in lower case using Nokia Pure Headline Light. Slide titles should be in sentence case using Nokia Pure Headline Light.

Body copy text should be sentence case using Nokia Pure Text Light.


Documents

DWDM Basic Presentation