Limits of Fiber-Optic Communications Systems.indico.ictp.it/event/a06183/session/31/contribution/21/material/0/0.pdfAn introduction to nonlinear processes in Fiber Optic Communications

SMR 1829 - 14

Winter College on Fibre Optics, Fibre Lasers and Sensors

12 - 23 February 2007

Limits of Fiber-Optic

Communications Systems

Hugo L. Fragnito

Optics and Photonics Research Center UNICAMP-IFGW

Brazil

Hugo L. Fragnito

Optics and Photonics

Research Center

UNICAMP-IFGW

Tel. (xx55-19) 3521-5430

[email protected]

Limits of FiberLimits of Fiber--OpticOptic

Communications SystemsCommunications Systems

Limits of FiberLimits of Fiber--OpticOptic

Communications SystemsCommunications Systems

Goals:

Present an overview of the basic physical mechanisms that limit fiber

optic system performance

Understand physical limits of fiber capacity

An introduction to nonlinear processes in Fiber Optic

Communications Systems

333 H. Fragnito UNICAMP H. Fragnito UNICAMP H. Fragnito UNICAMP ––– IFGWIFGWIFGW

Transmission Capacity of Optical FibersTransmission Capacity of Optical Fibers

100 THz Bandwidth (loss < 0.5 dB/km)

Capacity = BxL (Bit rate x Distance)

• Coaxial (copper) cable:

25 Mb/s x km

Limited by loss

(skin depth effect)

• Optical Fiber:

> 1 Pb/s x km (?)

Limited by dispersion (?)

Over 1 million km transmission demonstrated with optical fibers.

BxL product is not a good specification for fiber capacity

How far can we go with fibers? (for a given bit rate)

L (

km

)

B (Gb/s)

Lo

ss,

(dB

/km

)Wavelength, (µm)

0.8 1.0 1.2 1.4 1.6 1.80.1

0.2

0.4

1.0

2

4

Water peaks

XXI century fiber

XX century fiber

96 THz


TopicsTopics

• Physical Limits from Linear Effects

• Attenuation and Dispersion limits

• Nonlinear optical effects

• Limits imposed by optical nonlinearities

ICTP 2007 H. Fragnito - Unicamp 5

LINEAR EFFECTS

Attenuation – Sensitivity

Chromatic Dispersion

Polarization Mode Dispersion

Effects limiting capacity of optical fiber transmission


Attenuation/Detection limitAttenuation/Detection limit

Minimum number of photons/bit at the receiver for a given error probability

(BER = 10-9)

p N( ) exp( )0 10 9

• Poisson statistics

• Quantum limit:

NQ = 21 photons

• Practical receivers:

N > 1000 photons

(Sensitivity)

Maximum fiber length to receive N photons/bit

for a given launched power, Ptx

0.1 1 10 100

100

70

80

90

300

200

N = 200

N = 21 (quantum limit)

L(k

m)

N = 2000

Ptx = 0 dBm

= 0.2 dB/km

= 1550 nm

B (Gb/s)

BER: Bit Error Rate


DispersionDispersion

DL

1

Measurement of Group Velocity Dispersion (GVD):

Received pulsesInput pulses(different

wavelength)

time

Single mode fiber, length L

++

time

Lo

ss

(d

B/k

m)

0.1

0.2

0.4

0.8

1.0

Wavelength (µm)

1.

3

1.

4

0

1.

5

0

Standard Fiber

Dispersion Shifted Fiber

(DSF)-10

0

20

10

S0= 0.075 (ps/nm

2)/km

1.

6

0

Dis

pers

ion

(p

s/n

m/k

m)

0 = 1550 nm

EDFA

SdD

d

0 = 1310 nm

Ga

in (

dB

)


Dispersion and ChirpDispersion and Chirp

Instantaneous frequency tc

Dzt

40

2

02

)(

0 t

0

t

Dispersion produces a frequency chirp in the bit pulse


Beyond the dispersion limitBeyond the dispersion limit

– Dispersion Compensation

tD > 0 tDc < 0

tDc < 0D > 0

L1L2 DcL2 + DL1 = 0

– Dispersion Compensating fibers introduce losses (use EDFAs)


Fiber BirefringenceFiber Birefringence

Imperfections in fabrication

Stress induced during cabling, installation

Polarization fluctuations (mechanical vibrations, temperature,…)

Beat Length LB = /(nx – ny)

Typically, nx – ny ~ 10-7

LB ~ 15 m @ 1550 nm

BEAT LENGTH

Slow axis

Fast axis

y

x


Slo

w a

xis

Input pulse

Output pulse

Polarization Mode Dispersion Polarization Mode Dispersion -- PMDPMD

Fast axis

DGD (differential group delay)


PMD in Long FibersPMD in Long Fibers

• In long fibers the birefringence axes are not preserved in orientation but vary, in average, after one “coherence length” (Lc)

• DGD follows a random walk process

(analogous to Örnstein-Uhlembeck process in Brownian motion theory)

Lc

cLLDGD


Attenuation, DispersionAttenuation, Dispersion,, and PMD Limitsand PMD Limits

0.001 0.01 0.1 1 10 100 10001

10

100

1000

Quantum limit for 1 mW transmitter2000 photons/bit

Z-DSF

Fib

er

len

gth

(km

)

Bit rate (Gb/s)

SDF

PM

D=

1p

s/

km

0.1

ps/

km

Attenuation limits for 1mW transmitter, = 0.25 dB/km and BER < 10-9

Quantum limit = 20 photons/bitSDF = Standard dispersion fiber (D = 17ps/nm/km)Z-DSF = Zero-Dispersion Shifted Fiber (D = 0, S = 0.07 ps/nm2/km)


PMD compensationPMD compensation

Polarization state varies randomly but slowly (> minutes)

Several techniques involving feedback on Dynamical Polarization Controller (DPC)

S. Yao, WDM, Nov. 2000

TX DPCt

PBS

Feedback

PMD

analyzer

TX DPCPBS

Feedback

PMD

analyzer

+

t

TX: TransmitterPBS: Polarization Beam Splitter

t: delay line


Linear effects limiting fiber capacity Linear effects limiting fiber capacity REVIEWREVIEW

• Attenuation – related to sensitivity of receiver

– Minimum number of photons per bit for BER < 10-9

– Typically 2000 photons (Quantum limit: 21 photons)

– Compensated by using optical amplifiers

• Dispersion – related to index profile and material dispersion

– Pulse (bit) dispersion given by spectral width of laser

– Standard dispersion fiber: D = 17 ps/nm/km @ 1550 nm

– Dispersion Shifted fiber : D = 0; Dispersion Limit given by Dispersion Slope

– Compensated using Dispersion Compensation Fibers (for WDM dispersion slope must also be compensated)

• Polarization Mode Dispersion (PMD) – related to fiber birefringence

– Orthogonal polarizations travel at different speeds

– Polarization fluctuates slowly with time (vibrations, temperature, stress)

– PMD can be compensated using polarization controller and feedback circuit

ICTP 2007 H. Fragnito - Unicamp 16

Nonlinear optical

effects in fibers

Stimulated Scattering SBS: Stimulated Brillouin Scattering

SRS: Stimulated Raman Scattering

Nonlinear refractive index (phase modulation)Phase Modulation

Solitons

Four Wave Mixing


• Effective area

Effective Area and Effective LengthEffective Area and Effective Length

• Effective Length

•• Nonlinear effects depend on light intensity (I = Power/Area)Nonlinear effects depend on light intensity (I = Power/Area)

Le

eff

L1

I 2dA

IdAAeff

80 µm2 for standard fibers

55 µm2 for DSF

Aeff

L0distance

po

wer

L for L << 1

1/ for L >> 1Leff

(ex., 0.22 dB/km,

1/ 20 km)

•• Nonlinearities are important over a length of fiber where intenNonlinearities are important over a length of fiber where intensity is high sity is high


Stimulated Raman Scattering (SRS)Stimulated Raman Scattering (SRS)

• Co-propagating scattering

• Coupling to molecular

vibrations of silica

• High power threshold

example: Pth 1.8 W

(Aeff = 80 µm2, Leff = 20km)

laser - vibr

laser

Pump Laser

0

2

4

6

6 12 180

Raman Shift (THz)

Ram

an

Ga

in (

10

-12

cm

/W)


Raman in Raman in DDWDM systemsWDM systems

SRS manifests as tilting of WDM spectrum

higher loss for channels with smaller ’s

wavelength

Po

wer,

dB

m


Stimulated Brillouin Scattering (SBS)Stimulated Brillouin Scattering (SBS)

laser - B

laser• Precludes long distance bi-

directional transmission

Strongest nonlinearity

Counter-propagating scattering

But easy to eliminate

• Threshold depends on laser linewidth

Example (20 km, 80 µm2): Pth = 8.4 mW (narrow line lasers) Frequency, GHz

Sig

na

l

10.6 10.8

B

B

g 4x10-9 cm/W

B

laser

eff

eff

thv

v

gL

AP 184


Phase ModulationPhase Modulation

• Self phase modulation

• Modulation of phase of the wave changes instantaneous frequency (t)

• Broadens pulse spectrum(t )P(t )

time, t

n = n0 + n2P(t)/Aeff

• Accelerates pulse

spreading by dispersion

n = n0 + 2n2 Pk(t)/Aeff• Cross phase modulation


Phase modulation and dispersionPhase modulation and dispersion

Spectral broadening is larger in fibers with lower dispersion [bad for WDM]

1542 1543 1544 1545 1546

-20

-15

-10

-5

0

5

10

15

OUTPUT (50 km)

INPUT

Inp

ut

po

wer

[dB

m]

Wavelength [nm]

-45

-40

-35

-30

-25

-20

-15

Ou

tpu

t p

ow

er

[dB

m]

D = 0

D = 17ps/nm/km

-150 -100 -50 0 50 100 1500

5

10

15

Ou

tpu

t p

ow

er,

mW

Time, ps

D = 17 ps/nm/km

4 mW

20 mW

But pulse broadening is larger in fibers with higher dispersion [bad for high bit rate systems]

Trade off between phase modulation and dispersion

(general philosophy in modern NZ-DSFs)


Limitations from Phase ModulationLimitations from Phase Modulation

Self Phase Modulation (SPM)

• Important in single channel systems

Cross Phase Modulation (XPM)

• Important in WDM systems

• Phase of one channel is modulated by the power of all other channels

– broadens pulse spectrum

– accelerating pulse broadening by dispersion

– Limits pulse duration and power ( P/ t)

– Pulse Duration limits the bit rate (B)

– Power limits the distance (L)

• Ultimate limit of DWDM systems?P.P. Mitra and J.B. Stark, Nonlinear limits to the information capacity of optical

fibre communications, Nature, 411, 1027-1030 (June 2001)


Four Wave Mixing (FWM)Four Wave Mixing (FWM)

– Most important effect for WDM systems with low dispersion

– Due to nonlinear refractive index

Reduces the transmitted power in each channel

Produces cross talk

P

P1 P2

P

1 2

1 22 1


FWM and dispersionFWM and dispersion

– FWM efficiency is larger in lower dispersion fibers

– Region around zero dispersion wavelength ( 0) extremely difficult for DWDM (“forbidden gap” )

– Non-Zero Dispersion Shifted (NZD) fibers alleviates the problem

-70

-60

-50

-40

-30

-20

-10

0

1530 1535 1540 1545 1550 1555 1560

1 (nm)

FW

M e

ffic

ien

cy,

(dB

)

0 = 1550 nm0 = 1570 nm

0 = 1310 nm

Forbidden gap

2

2

22

2

1

)2/(sin41

L

L

e

Le

DSF

NZD

SMF


Limitations by FWMLimitations by FWM

5% Power penalty

1

10

100

1000

0.001 0.01 0.1 1 10 100 1000

D (ps/nm/km) Ptx (dBm)

17 39

-1.4 26

0 6.3

D = 17 ps/nm/km

D = -1.4 ps/nm/km

D = 0

Dispersion limit

B (Gb/s)

L(k

m)

FWM limit


SS -- ,C,C -- and Land L -- bands for DWDMbands for DWDM

Lo

ss (

dB

/km

)

0.1

0.2

0.4

0.8

1.0

Wavelength (µm)

-10

0

20

1.3 1.40 1.50

10

1.60

Dis

pers

ion

(p

s/n

m/k

m)

0 = 1320 nm

Dry Fiber

OH peak

1550 nm

S- C- L- band

NZ-DSF+

NZ-DSF low slope

DSFNZ-DSF-

Standard SM fiber


Raman amplificationRaman amplification

Ram

an

Gain

, d

B

Signal Wavelength, nm

1460 1500 1540 1580 16200

5

10

15

20

Raman Gain

40 nm centered in any

wavelength

>90 nm combining pump lasers

Distributed gain:

fiber now has gain instead of

loss

can use low power

transmitter (mitigates

nonlinearities)

Can be used for D = 0

Raman Pumps (14XX nm)


SummarySummary

• Attenuation, Dispersion and PMD limits can be overcome with Optical Amplifiers, Dispersion Management and Compensation techniques

• Maximum capacity in practice: DWDM systems > 10 Tb/s x Mm (in the lab)

Limited by bandwidth of available amplifiers and nonlinearities

• Capacity of fiber transmission is limited by nonlinear optical effects– Moderate and High dispersion fibers: XPM

– Low dispersion fibers: FWM

• Nonlinearities can be reduced by – Large area fibers

– Dispersion management strategies (D large, average D = 0)

Compensate also for dispersion slope

– Operate the system in |D| > 2 ps/nm/km region (L band, S band,…)

– Distributed Raman Gain: loss-less fiber (no need to use high power)


Where to get more informationWhere to get more information

• G.P. Agrawal, Fiber-Optic Communication Systems, 3rd ed., Wiley, New York, 2002.

• WDM Solutions, PenWeell, free subscription: www.optoelectronics.world.com

• R. Ramaswami and K. N. Sivarajan, Optical Networks, 2nd ed., Morgan Kaufmann, San

Francisco, 2002.

• Optical Fiber Communications Conference Proceedings (OFC), Optical Society of America,

Washington, DC, (1973-2002).

• Optical Fiber Telecommunications, Vols. III-A, III-B, I.P. Kaminow and T. Koch, Eds. (1997);

Vols. IV-A and IV-B, I.P. Kaminow and T. Li, Eds., (2002), Academic Press, San Diego.

• E. Desurvire, D. Bayart, B. Desthieux, S. Bigo, Erbium-Doped Fiber Amplifiers: Device and

System Developments, Wiley, New York, 2002.

• E. Desurvire (Guest editor), C. R. Phyisique, Dossier: Optical Telecommunications, 4(1), 2003.

2/15/2007 Hugo Fragnito 1

Prof. Hugo L. Fragnito

Optics and Photonics Research Center – CePOF-Unicamp

Physics Institute, State University of Campinas – UNICAMP-IFGW

Campinas, SP, Brazil

[email protected]

UNICAMP - IFGW

Fiber-Optic Parametric

Devices


Optical Amplifiers for DWDMOptical Amplifiers for DWDM

EDFA (1510-1620 nm) Erbium

TDFA (1440-1510 nm) Thulium

SOA (60 nm bandwidth)

Semiconductor Optical Amplifier

Raman Amplifiers (40 nm bandwidth;

choice of spectral region)

1520 1540 1560 1580 1600 1620 16400

10

20

30

40

Gain

(dB

)

Wavelength (nm)

C-band L-band

EDFAs

90 nm

Limited by Nature to ~ 100 nmPhysics: Quantum energy levels

Chemistry: Special materials

Ram

an

Gain

, d

B

Signal Wavelength, nm

1460 1500 1540 1580 16200

5

10

15

20

Raman Gain


The ideal optical amplifierThe ideal optical amplifier

• Explore the full capacity of silica fibers

(1250-1650 nm) with a single device

54.5 THz bandwidth1164 channels @ 40 Gb/s = 46.6 Tb/sM x 46.6 = 140 Tb/s (M = 3) for M-ary format

• 400 nm bandwidth, flat gain spectrum, high output power

• Is it possible?

• Do we need it? Do we want it?

• If yes, probably the only option is the FOPA (Fiber-Optic Parametric Amplifier)

• But FOPDs can do much more than just amplify signals…L

os

s (

dB

/km

)

Wavelength (µm)

0.8 1.0 1.2 1.4 1.6 1.8

0.1

0.2

0.5

1.0

2

4

55 THz


WDM NetworkingWDM Networking

• WDM networks need new functionalities

– Add and Drop Channels Optically

– Wavelength Routing Assignment

– Wavelength reuse

• Wavelength Conversion

• Wavelength Exchangers

• FOPDs met the needs of WDM networking

OADMOptical Add & Drop Multiplexer

2/15/20072/15/20072/15/2007 Hugo FragnitoHugo FragnitoHugo Fragnito 555

FOPAs

• Spectral region not limited by energy levels of the medium – can be

optimized by engineering waveguide dispersion

• Large gain, flat gain spectrum, large bandwidth, low noise

• Based on ~ phase matched FWM

• Idler wave generated

• can be used as wavelength converter

• Typical pump power, fiber length, gain, bandwidth, noise figure:

• P = 0.1 – 1 W,

• L = 0.2 – 5 km,

• G = 20 – 40 dB (up to 70 dB demonstrated)

• 3dB = 20 – 60 nm (100 nm demonstrated)

• NF = 3.5 – 4.5 dB (0 dB in phase sensitive mode)

Fiber-Optic Parametric Amplifiers

p si

i = 2 p - s


Single pump or

1P-FOPA

Double pump or

2P-FOPA

Two Types of FOPA

)(ˆ)(ˆ)(ˆ *2)3(

043

ipsNL EEP

• Broader gain spectrum• Flatter gain spectrum• Narrow-band idler

s p

p si

i s

1 si 2

)(ˆ)(ˆ)(ˆ)(ˆ *

21

)3(

023

isNL EEEP

• Simpler


FOPA Basic Components

Single pump FOPA

Double pump FOPA

L

Pump laser

Pump-signal

coupler

Signal ( s)

p

Nonlinear, low

dispersion fiberInput Output

Filter

Pump out

L

Pump-signal

coupler

Signal ( s)Nonlinear, low

dispersion fiberInput Output

Pump lasersp1

p2 Filter


Gain spectrum

Tunable Laser

1P-FOPA

EDFA

OSA

0

0

Tunable Lasers

1

2

MUX

OSA

2P-FOPA


Gain and Phase Matching

W1.0P1 =

nm16001 =

W0.50P2 =

W0.50P1 =

nm1628.6252 =

nm15721 =

0

5

10

15

20

25

30

35

40

G, d

B

Parametric Gain

1P-FOPA 2P-FOPA

1550 1560 1570 1580 1590 1600 1610 1620 1630 1640 1650

Wavelength, nm

T(

km

-1)

-50

-40

-30

-20

-10

0.0

Wavevector mismatch

W-1/km2.4=

dB/km0.20=

km2.0L =

nm1600ZD =

ps/nm2/km0.065SZD =

Parametric processes depend critically on phase matching conditions

2 – 1 = 52 nm, P1 = P2 = 2.2 W

0 = 1568.2 nm, L = 0.95 km, = 4.0 dB/km, (Leff = 0.63 km)= 2.1 W-1/km, 3 = 0.11 ps3/km, 4 = -5.5x10-4 ps4/km

Tuning the central pump wavelength of a 2P-FOPA


1568.2 nm

Parametric Gain

0.00

10.00

20.00

30.00

40.00

50.00

60.00

1520 1530 1540 1550 1560 1570 1580 1590 1600 1610 1620

Wavelength, nm

G(d

B)


FOPD examples

1550 nm to 500 nm (visible) wavelength conversion

375 THz (1020 nm) translation!

20 m PCF with = 70 W-1/km,

01 = 750 nm, and 02 = 1260 nm R. Jiang et. al., OFC 2006

S. Radic et al., OFC 2003

Conversion with phase conjugation (dispersion compensation)

360 km transmission over standard (D = 16 ps/nm/km) fiber

5 DWDM channels at 10 Gb/s

2P-FOPA (HNLF, 1 km), orthogonal pumps, counter-phase

modulation

80 km 160 kmz = 0 km 240 km 320 km

FOPA*


Wavelength conversion

Simulation vs.

measurements

0 2 4 6 8 10 12 14 16 180

10

20

30

40

50

60

70

80

90

100

En

erg

y C

on

vers

ion

, %

Input Power, mW

SimulationMeasurements

J.M. Chavez Boggio et al., PTL 15, 1528 (2003)

• FOPDs can convert wavelengths with gain

• Broadband, tunable

• Transparent to bit rate/protocol to > 1000 Gb/s

• L-C-S-… Band conversion

• Almost 100% energy conversion (pump to signal+idler)


All-optical regenarion

High order idlers generated by cascaded FWM can

reduce noise (fluctuations in levels “0” and “1”)

S. Radic et al., PTL 2003

Wavelength ExchangerWavelength Exchanger

)()()()( 32*

1)3(

023

4 EEEPNL

Input Output

Po

we

rd

en

sit

y

Frequency, (THz)

192.8 193.0 193.1192.9

Simultaneous exchange of the

modulation signals carried by

two different channels

(without ADD or DROP devices)

)2sin()2cos()(

002010 PLeAiPLAA

i

sii

K. Uesaka et al., IEEE-JSTQE 8, 560 (2002)

)(ˆ)(ˆ)(ˆ)(ˆ21

*)3(

023

isNL EEEP

if 2 PL = /2 10


Spurious FWM under control

Short fibers

Uniform fibers

Up to 16 mW per channel (x10 channels) can be

extracted from a 0.8 km DSF 2P-FOPA pumped at 4.4 W

(22 dBm total signal output power)

J.M.C. Boggio et. al., PTL 17, 1842-1844 (2005);Opt. Comm. 259, 94-103 (2006)

J.L. Blows Opt. Comm. 236,115 (2004).

(G = 40 dB)

FW

M P

ow

er

(dB

m) 4

-12

-8

4

0

12 13 14 15 16 17 18

Output signal Power (dBm)

1550 1560 1570 1580

1 10.....

Wavelength, nm

Po

we

r, d

Bm

-10

10

20

0

10 1.....Signals Idlers

Slope 3

1555 1560 15651550

-5

0

5

10

15

Po

wer,

dB

m

Wavelength, nm


Stimulated Brillouin Scattering

Big problemUsually solved by broadening pump spectrum

But this induces gain fluctuations

idler broadening

Sensitiveness to 0(z) fluctuations

-4 -2 0 2 4

-80

-75

-70

-65

-60

-55

-50

-45

Po

wer

sp

ectr

um

(d

Bm

)

Relative frequency (GHz)-4 -2 0 2 4

(nm)

0.16 nm

=1566.9 nm0

s= 1560 nm

0.25 nmD (

ps/

nm

/km

)

J.M. Chavez Boggio et al., Opt. Comm. 249, 451 (2005)

( 0 = 0.1 nm)


Mitigating SBS

Varying elastic properties along fiber length

Stain (or temperature) modifies the sound velocity, producing a shift in Brillouin frequency

A strain (or temperature) distribution along the length of the fiber (inhomogeneously) broadens the Brillouin spectrum, increasing the SBS threshold.

J. Hansryd et al., JLT 19, 1691 (2001)

4.8 dB

5 10 15 20 25 30

-60

-50

-40

-30

-20

-10

0

10

20Without strain distributionWith strain distribution

Back

sca

tte

red

po

wer

(dB

m)

Input power (dBm)

10.7 dB

10 dB

J.D. Marconi e al., ECOC’2005


SBS: B(z) and 0(z)

Brillouin frequency B = 2 optV/c

Sound velocity V =(stress/density)½

Temperature d B/dT = 1 MHz/K

Strain d B/dS = 460 MHz/%

Zero-dispersion wavelength also varies:Temperature d 0/dT = 0.03 nm/K

Strain d 0/dS = 2 nm/%

Can be used together to suppress SBS and control 0(z)

No

rma

lize

d p

ow

er

(dB

)

Frequency shift (GHz)

705 MHz

9.4 9.6 9.8 10.0 10.2

unstrained

strained

-10

-8

-6

-4

-2

0J.D. Marconi et. al., ECOC’2005


Example: Wavelength Converter

Strain suppressed SBS

70 nm signal tuning range (1548 – 1618 nm)

Narrow line idler (100 kHz pump width)

J.D. Marconi et al., ECOC’2005


Low SBS fibers

Photonic Crystal Fibers

Acoustic and optical confinement

Strong interaction but low coupling between optic

mode and acoustic modes

P. Dainese et al., Nature Phys. 2, 388, 2006

Optical mode

Acoustic mode

+-

+

• Standard telecom-compatible fibers: 4 dB SBS threshold increaseM.V. Vaughin et al., JON 5, 40 (2006)

SBS threshold increase by 7 dB

Core diameter

(1 µm)

• FOPAs for DWDM can be superior to Semiconductor, Erbium, and Raman

amplifiers

– in bandwidth

– in gain flatness

– in noise figure

• Parametric processes can be used in a variety of functions for optical

networking (wavelength conversion/exchange) and signal processing

(phase conjugation, power limiting, all optical switching, fast tunable

filters…)

• Fibers for further progress: uniformity, tailored dispersion, highly

nonlinear but low SBS

• As new fibers (photonic crystal or conventional) become available with

optimized designs, FOPDs may revolutionize optical communications

ReviewReview


Optical Communications LaboratoryOptical Communications Laboratory

Students 4 André Guimarães

Andrés Rieznik

Gustavo Wiederhecker

Henri Okajima

Res. Assoc. 1 José Manuel Chávez Boggio

Pos-Doc 1 Diego Marconi

Technicians 1 Vagner Cardoso

Faculty 1 Hugo Fragnito

Documents

Limits of Fiber-Optic Communications Systems.indico.ictp.it/event/a06183/session/31/contribution/21/material/0/0.pdfAn introduction to nonlinear processes in Fiber Optic Communications