OutlineHistory of lightwave undersea cable systemsOptical amplifier technologiesExamples of lightwave undersea cable networks
� TPC-5CN� APCN� FLAG� JIH
Future technologies� WDM� Optical Soliton
Transmission capacity of the underseacable systems in the Pacific ocean
.
20102005200019951990198519801975197019651960RFS Year
N u m b e r o f v o i c e c h a n n e l s
10
100
1K
10K
100K
1M
10M
TPC-1(Coaxial)
TPC-2(Coaxial)
TPC-3(Lightwave)
TPC-4(Lightwave)
TPC-5CN(Optical amplifier)
TPC-6(WDM or Soliton)
10 times capacity increase for every 10 years!
Lightwave undersea cable systemsin the Pacific ocean
TPC-5CNTPC-4
TPC-3
Major system parameters ofTPC-3 and TPC-4 system
TPC-3 TPC-4Signal wavelength 1.3m 1.55m
Bit-rate 280Mbit/s 560Mbit/sModulation scheme IM-DD IM-DD
Repeater spacing 50km 120kmLight source FP-LD DFB-LD
Photo detector Ge APD InGaAs APDPower supply current DC 1.6A DC 1.6A
Transmission loss characteristics of the SiO2 based optical fiber
.
1.71.61.51.41.31.21.11.00.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Wavelength (m)
T r a n s m i s s i o n L o s s ( d B / k m )
1.3mwindow
1.55mwindow
Basic system configuration of the lightwave undersea cable system
.
Term
inal
Equ
ipm
ent
Term
inal
Equ
ipm
ent
TerrestrialLinks
TerrestrialLinks
Powerfeeding
equipment
Rep.-1 Rep.-2 Rep.-n
System length
Opticalfibers
Powerfeeding
line Powerfeeding
equipment
Oceanground
Oceanground
Block diagrams of the repeater circuits.
PD LD
LD(STB)
EQLAMP
Decision
Timing
LDDriver
LDDriver(STB)
Cou
pler
SV1(OOS)
SV2(IS)
Inputfiber
Outputfiber
PDLD
LD(STB)
EQLAMPDecision
Timing
LDDriver
LDDriver(STB)
Cou
pler
SV1(OOS)
SV2(IS)
Inputfiber
Outputfiber
Downstream link
Upstream link
Reliability issues of the optical repeater
Component Target FIT Numbers Total FIT APD module 1.0 1 1.0 Optical switch 1.0 1 1.0 MIC(3R) 0.5 3 1.5 MIC(SV) 1.0 2 2.0 Transistor 0.2 2 0.4 Diode 0.2 5.5 1.1 L,C,R 0.01-0.05 320 5.8 SAW 0.5 1 0.5 Others 1.6 Total 14.9FITs
LD module less than 28 2(act&sb) 0.8
Design target : not more than 3 ship repair during the life-time (life-time = 25years) MTBF 10years less than 16FITs per one repeater (FIT = 109 hours / MTBF)
OutlineHistory of lightwave undersea cable systemsOptical amplifier technologiesExamples of lightwave undersea cable networks
� TPC-5CN� APCN� FLAG� JIH
Future technologies� WDM� Optical Soliton
Principle of the Erbium-doped fiber optical amplifier (EDFA)
Er3+ Er3+
electronGroundlevel
Excitationlevel
photonabsorption
Er3+
non-light emissiontransient
Er3+
stimulated emissionto amplify signal
thermal equilibriumstate
Basic configuration of the EDFA
WDMcoupler
Pump LD
Er-dopedfiber
Optical isolatorOutputInput
Example of electro-optic repeater and EDFA
LD(STB)
Supervisory
LD driver(STB)
LD(ACT)
PD(Inside)
LD driver(ACT)
Erbium-doped fiber
WDM coupler Optical isolator
Pump LD
Electro-optic repeater EDFA
Technical difficulties of the lightwave undersea systems using EDFA repeater
Optical noise (ASE) accumulationChromatic dispersion of the transmission fiberNonlinearity of the transmission fiberPolarization dependent factors
� Polarization dependent loss (PDL)� Polarization hole burning (PHB)� Polarization mode dispersion (PMD)
Test bed of the lightwave undersea systems using EDFA repeater
OutlineHistory of lightwave undersea cable systemsOptical amplifier technologiesExamples of lightwave undersea cable networks
� TPC-5CN� APCN� FLAG� JIH
Future technologies� WDM� Optical Soliton
TPC-5CN Cable Route(Trans-Pacific Cable 5 Network)
NinomiyaJapanMiyazaki
Japan
Tumon BayGuam
KeawaulaHawaii
BandonOregon
San Louis ObispoCalifornia
APCN Cable Route(Asia-Pacific Cable Network)
MiyazakiJapan
PusanKorea
TouchengTaiwanLantau
Hong Kong
BatangasPhilippines
PetchaburiThailand
AncolIndonesia
ChangiSingapore
MersingMalaysia
FLAG Cable Route(Fiberoptic Link Around the Globe)
PorthcurnoU.K.
EsteponaSpain
PalermoItaly
Port SaidAlexandria
SuezEgypt
FujairahU.A.E.
BombayIndia
PenangMalaysia
Satun & SongkhlaThailand
LantauHong Kong
ShanghaiChina
KojeKorea
MiuraJapan
Major system parameters of OS-A system
Line bit rate 5Gbit/sSignal wavelength 1558.5nmInput signal level -20dBm to 0dBm
Repeater gain 7dB to 20dBNoise figure 5dB to 6dB
Optical amplifier Erbium doped fiberPump laser InGaAsP/InP diode
Pump wavelength around 1475nmPower feed current DC 0.92A
Reliability less than 10FIT/fiber pair
JIH Cable Route(Japan Information Highway)
To USA
To Russia
To Korea
To China
To Asiaand Europe
Major system parameters of JIH cable(tentative)
Line bit rate 100Gbit/sSignal wavelength 1530nm to 1570nm
Noise figure 5dB to 6dBOptical amplifier Erbium doped fiber
Pump laser InGaAsP/InP diodePump wavelength around 1475nm
Key technologyWavelength division multiplexing (WDM)100Gbit/s = N wavelength 10 or 5 or 2.5Gbit/s
OutlineHistory of lightwave undersea cable systemsOptical amplifier technologiesExamples of lightwave undersea cable networks
� TPC-5CN� APCN� FLAG� JIH
Future technologies� WDM� Optical Soliton
Explanation of Wavelength Division Multiplexing (WDM) technology
wavelength wavelength
Conventional systemOnly 1 signal wavelength
WDM systemMultiple signal wavelength
Transmission capacity per fiber is multiplied by the number of signal wavelength.
Technological difficulties - Signal multiplex/demultiplex - Optical amplifier bandwidth limitation - Inter-channel interaction due to optical fiber nonlinearity (so called four-wave mixing and cross-phase modulation)
Explanation of optical soliton technology
Conventional NRZ pulse(broad, pulse width = 1/bit-rate)
Optical soliton pulse(short, pulse width < 1/bit-rate)
Transmission bit-rate per signal wavelength can be expanded.
Technological difficulties - Optical short pulse generation - Inter-symbol interference (so called Gordon-Haus timing jitter)
Principle of recirculating loop experiment
Transmitter Receiver
SWON
SWOFF
SWON
SWOFF
1loop 1loop
2loops
3loops
Time
(1) Load the optical signal intothe fiber loop
(2) Optical signal runs throughthe fiber loop repeatedly
(3) Number of recirculation canbe determined by the timing
Experimental setup of 5Gbit/s, 22WDM,9500km recirculating loop experiment
.
DFB-LDs
5Gbit/sOptical
Receiver
OpticalBandpass
FilterSMF or DCFEDFA
3dBFibre
Coupler
Optical Switch
Span 1(DSF)
Span 2(DSF)
Span 3(DSF)
Rep. 2
Rep. 3
Rep. 18
Span 18(SMF)
BoosterEDFA
LN mod.
1
2
22
Star
Cou
pler
Rep. 19
PolarizationScrambler1548.9nm
Optical Switch
1549.3nm
1557.3nmif required Rep. 1
~40km
~40km~40km
~40kmLoop length = 732kmZero dispersion wavelength = 1555nmRepeater output power = +8dBm Fabry-Perot
etalon
Span 8(DSF)
Span 9(SMF)
Rep. 9~40km ~40kmSpan 17
(DSF)~40km
Snap shot of the WDM experiments
Transmission performance of 5Gbit/s, 22WDM,9500km recirculating loop experiment
.
1558155715561555155415531552155115501549154815.0
15.5
16.0
16.5
17.0
17.5
18.0
Signal Wavelength (nm)
M e a s u r e d Q - f a c t o r ( d B )
BER = 10-9
Experimental setup of 20Gbit/s, 8100km straight line optical soliton transmission
DFB-LD EA-MOD
10GHz CLOCK
Transmitter
8123km transmission line
O/E PLL
DEMUX 10Gbit/sOR
EDFA
Receiver
rep-240 rep-1DCFOBPF
10GHzCLOCK
10Gbit/sDATA
20Gbit/s
LN-MOD
10Gbit/s DATA
MUX
Q
polarisationscrambler
pulsecompressor
Q
Transmission performance of 20Gbit/s, 8100km straight line optical soliton transmission
.
10000100015
20
25
30
loopstraight
distance (km)
Q-f
acto
r (dB
)
5000
20 Gbit/s
BER = 10-9
ConclusionTechnologies of the global lightwave undersea
cable networks are reviewed.WDM and soliton are two key technologies of
future undersea cable networks.100Gbit/s class lightwave communication system
is already available under the laboratory condition, and will be available for the commercial use in early 21st century.
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