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20-3-2007
Fotonica in SURFnet6Wouter HuismanNetwerkdiensten, SURFnet
2
Agenda
- Fibers & Infra- Module Blocks
- Transmitter, Receivers, Amplifiers, Filters- Systems
- Single channel lasers/receivers- Amplified single channel- C/DWDM
- DCM, PMD, FEC- Latest technology- SURFnet’s network
3
Optical fiber - Historical perspective
- Internal reflection known from
19th century (John Tyndall, 1870)
- Early fibers with cladding
extremely lossy ~1000dB/km
(1960)
- Today fiber loss ~0.2dB/km
Refractive indexN1(water) > N2 (air)
4
Fiber basics
- Multi Mode (MM)- Intra office- SX- max 500m
- Single Mode (SM)- LX, ZX, C/DWDM
5-10µm
50 - 62µm
CoreCladding
5
Fiber Loss (SM)
- Fiber loss is wavelength dependent, minimum is around 1550nm
1310nm 1470nm-1620nm
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Fiber plant layout
Equipment
POP
Splice
HandholePatching at ODF
MMR
~4km ~4km
7
Fiber Plant test
Basic paramaters:- Length- Loss- Reflection
OTDR (optical time domain reflectometer)
8
10Gb/s optical transmitter technologies
DFB
External Modulation - DM-DFB (Directly Modulated Distributed Feed Back laser)
• Cheap, small, low power consumption
• Chirped, i.e. different wavelength during “ones” and “zeros” which leads to a wide optical spectrum and associated transmission impairments
• Used for short reach transmission
{0,1,1,0,1,1,…,0,1,0}
DFB
{0,1,1,0,1,1,…,0,1,0}
Mach-ZehnderLiNbO3 modulator
External Modulation - CW-DFB (Continuous Wave DFB laser) and MZ (Mach-Zehnder) combination
• Expensive, relatively large, high-power drivers (high power consumption)
• Excellent performance
• Typically used for DWDM (Dense Wavelength Division Multiplexing)
9
Typical optical receiver setup
preamp AGC
CLK
decisioncircuit
(A)PD
Prec (dBm)
BER
10-12
10-9
10-6
Psens
data
10
Traditional optical fiber transmission systems
- Combination of transmitter and receiver connected directly to dark fiber
- Typical distance is max 100km- 150Mb/s -2.5Gb/s
Tx Rx
PT (dBm) PR (dBm)
Transmission fiber
α (dB/km)
Transmission distance = (PT-PR) / α (km)
11
3R regeneration - OEO
Transmitter – Receiver = 3R
- Re-amplification
- Re-timing
- Re-shaping
Tx Rx Tx Rx Tx Rx
12
EDFAs (Erbium Doped Fiber Amplifiers)
• Fiber doped with Er3+ ions be excited by 980nm or 1480nm photons• Spontaneous emission generates noise• Excited state Erbium ions can be stimulated to decay to ground state via stimulated emission by a 1550nm signal
Pump laser
Incoming
Outgoing
13
Single Channel System with amplifiers
Tx RxOAOA
Pre and Post Amplifiers allow for longer single span Systems upto 240km
-150Mb/s -2.5Gb/s
Tx OLAOA RxOAOLA
14
Wavelength Division Multiplexing (C/DWDM)
- WDM filters, passive device
- Muxing coloured wavelength
- Spacing between ’s determines the number of channel per fiber
- SURFnet’s DWDM supports 72 ’s @ 10Gb/s
15
DWDM System
OADM Node
Mu
x
Terminal Node AMP NodeOEO
OEO
…
Mu
xOEO
OEO
…
DCF
DCF
DCF
DCF
DCF
DCF
DCF
DCF
OEO
OEO
…
OEO
OEO
…
DCF
DCF
Dem
ux
Dem
ux
Terminal Node
OEO
• Typically 80 channels spaced at 100GHz using C and L band• Each channel operating at 10Gb/s, thus 800Gb/s per fiber• Limited Optical Add and Drop for point-to-point optical lightpaths
16
Chromatic Dispersion
- Typical value dispersion (D) 17ps/nm*km
Transmission
Rate
Spectral
Width (F)
Bitperiod(T
b)
Max distance
(km)
2.5Gb/s 0.025 4x10-10 800
10Gb/s 0.1 1x10-10 50
40Gb/s 0.4 2.5x10-11 3
T ~ bitperiod
L = Tb/ F*D
10Gb/s
F
17
Chromatic Dispersion
After 120km transmission
Speed of Light is Wavelength dependent: Chromatic dispersion affects pulse shape
1 2
1 2
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
4100 4300 4500 4700 4900 5100 5300 5500
Time (ps)
Opt
ical
Pow
er (A
.U.)
Optical pulse shape at transmitter output
Tx
120km standard SMFD=17.8 ps/nm km
RxOA ƒ
120km-10Gb/s system configuration
rb = 10Gb/s
c = 1557nm
OA
011101101001001 011101101001001
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PMD
20
FEC
- Forward Error Correction
- Technique to improve bit error rate resulting better Preceiver
- Adding FEC increases bitrate worse Preceiver
Transmit Receive
1 0 0 1 0 1 0 0 1 00 1 1 1 1 0 1 0 1 10 0 1 0 1 0 0 1 0 11 0 1 1 1 1 0 1 1 10 1 1 1 1 0 1 1 1 1
Prec (dBm)
BER
10-12
10-9
10-6
Psens
FEC on
Parity check indicates the single error bit
21
New developments
- 40Gb/s and 100Gb/s- QPSK/QAM 40G over 10Gb/s
From Static to Dynamic:- MEMS – Switchable mirrors
- Dynamic WDM- eDCM- Tunable lasers- Tunable filters- DRAC
22
Layer 0 Evolution
Advanced FEC
Advanced Signal Processing
Higher Spectral Efficiency(QPSK/QAM)
Remove Raman, Increase Performance
Remove DCMs & Amps, Increase PMD Tolerance, Eliminate complex engineering rules (esp. OADM)
4x Capacity per Line and 40G Service Support
OADM NodeM
ux
Terminal Node AMP NodeOEO
OEO
…
Mu
xOEO
OEO
…
DCF
DCF
DCF
DCF
DCF
DCF
DCF
DCF
OEO
OEO
…
OEO
OEO
…
DCF
DCF
Dem
ux
Dem
ux
Terminal Node
Ram
an
Ram
an
Ram
an
OEO
Mu
x
OEO
OEO
… OEO
OEO
…Dem
ux
OEO
ROADM NodeTerminal Node AMP Node Terminal Node
23
Dynamic Networking
ROADM
SMF-28
SMF-28
SMF-28
E-LEAF
E-LEAF
E-LEAF
TWcTWc
ROADM
ROADM
ROADM
ROADM
ROADM
24
SURFnet6
• third generation DWDM• 10Gb/s per channel• 50GHz channel spacing• wavelength locking• optical add/drop• forward error correction• dispersion compensation• C-band, can be upgraded to add L-band
Dordrecht1
Breda1
Tilburg1
NLR
BT
BT
NLR
BT
Zutphen1
Lelystad1
Sub network 4: Blue Azur
Subnetwork 3: Red
Sub network 1: Green
Subnetwork 2: Dark blue
Subnetwork 5: Grey
Emmeloord
Zwolle1
Venlo1
Enschede1
Groningen1
LeeuwardenHarlingenDen Helder
Alkmaar1
Haarlem1
Assen1
Beilen1
Meppel1
Emmen1
Arnhem
Apeldoorn1
Bergen-op-Zoom
ZierikzeeMiddelburg
Vlissingen Krabbendijke
Breukelen1
Ede
Heerlen2
DLO
Schiphol- Rijk
Wageningen1 Nijmegen1
Hilversum1
Hoogeveen1
Lelystad2
Dwingeloo1
Amsterdam2
Den Bosch1
Utrecht1
Beilen1
Nieuwegein1
Heerlen1
Heerlen1
Maastricht1
Eindhoven1
Maasbracht1
Rotterdam4
3XLSOP
I BG1 & I BG2Middenmeer1
NNII nHolland
SchipholOegstgeest
Lisse
ZoetermeerLSOP Rtd
SWOVNBD
DenHaag
Rotterdam1
Delft1
Leiden1
Amsterdam1