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We propose an Ultra-Dense Wavelength Division Multiplex Passive Optical Network (UD-WDM-PON) based on homodyne detection in a totally transparent ring-tree implementation. It is based on time switching phase diversity homodyne detection and local oscillator reuse for upstream transmission. 4 GHz spaced 1Gb/s streams were correctly received in a 30 km experimental deployment serving 1024 users.
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Universitat Politècnica de Catalunya (UPC)Dept. of Signal Theory and Communications (TSC)
Optical Communications Group (GCO)www.tsc.upc.edu/gco
Univ
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itat
Politè
cnic
ade C
ata
lunya
UltraUltra--Dense, Transparent and Resilient Dense, Transparent and Resilient
RingRing--Tree Access Network using Tree Access Network using
CouplerCoupler--based Remote Nodes and based Remote Nodes and
Homodyne TransceiversHomodyne Transceivers
Josep M. Fabrega and Josep [email protected]
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OpticalOpticalOpticalOptical accessaccessaccessaccess evolutionevolutionevolutionevolution
TIMECATV
ADSL
FTTH-PtP
FTTHG/E-PON
FTTHWDM-PON
POTs
FTTH
WDM&TDM-PON
COST
xDSL
TIME
CAPACITY
FTTH ultra-dense WDM-PON
ngPON
WDM - PONWDM - PON
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WDM
TIME
TDM
� Few wavelengths
� High-speed
∙ Rb>>BWu
∙ Power consumption
� 1000 wavelengts
� Low-speed
∙ Rb = BWu
∙ Lambda-to-the-user
IntroductionIntroductionIntroductionIntroduction
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IntroductionIntroductionIntroductionIntroduction
� Migration from TDM/WDM to pure WDM
� Ultra-dense WDM PONs
∙ Multiple low capacity channels
� E.g. 1 Gbps
λ
More than 1500 ch. at C band
...........................
3 GHzOL
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IntroductionIntroductionIntroductionIntroduction
∙ IM-DD systems limited by:
� Sensitivity
�Optical filters selectivity
∙ Coherent systems
�Heterodyne
– Image frequency problems
�Homodyne
– oPLL (phase lock problems)
– IQ, Feed-Forward, Phase Diversity
LocalLaser
+
-
+
-OpticalInput Ip(t)
λ
...........................
3 GHzλLO
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IntroductionIntroductionIntroductionIntroduction
Locallaser
+
-
Data and Phase
recovery
IM or PM
Data
DataReceiver
TransceiverDPSK Downstream
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Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver
� Phase diversity achieved by switching local laser phase
� 3 dB penalty with respect to an ideal homodyne system due to the phase switching
� Several schemes proposed
I Q
t0 t0+T/2 t0+Tt
I Q
t0+3T/2 t0+2T
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Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver
Laser
CLKRecovery
+
-
PhaseScrambler
Tb
Tb
Tb/2
Data out
OpticalInput
I’
Q’
Vout
+
I’
Q’
outV
[1] J. Prat and J. M. Fabrega, ECOC 2005, Glasgow, Scotland, sept. 2005, paper We.P.104
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UPC Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase & & & & PolarizationPolarizationPolarizationPolarization
DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver
Laser
CLKRecovery
+-
PhaseScrambler
Tb
Tb
3Tb/2
Data out
OpticalInput
Pol. Scrambler
freq. doubler
Tb
Tb/2
Tb
Tb/4
0º
90º
H
V
[3] J. M. Fabrega and J. Prat, OFC 2006, Anaheim CA, March 2007, paper JThB45
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Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver
Laser
CLKRecovery
+
-
PhaseScrambler
Tb
Data out
ES(t)
Tb/2ELO(t)
IP(t) I f(t)
Transmission experiments (1Gbps) [2]:• -38 dBm sensitivity @ BER 10-9
• 18 MHz linewidth tolerance @ BER 10-3
• 100 MHz detuning tolerance• WDM Channel spacing of 3 GHz @ 1 dB Penalty BER 10-9
[2] J. M. Fabrega and J. Prat, OSA Optics Letters, vol. 32, no. 5, pp. 463-465, March 2007
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Network Network Network Network topologytopologytopologytopology and and and and wavelengthwavelengthwavelengthwavelength planplanplanplan
x/y coupler x/y coupler
50/50 couplerRNn
λ
C band
..................
4 GHz
CO
CPE
RN2
RNnWest
East
RN11:K powersplitter
CPECPE
CPE
CPECPE
CPE
2 splittersper RN
� Ring+trees PON (SARDANA-like)
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Central Office Central Office Central Office Central Office schemeschemeschemescheme
� DFB lasers + splitters + switches + EDFA
� Double fiber architecture
∙ No Rayleigh Backscattering
WestCO
EastTx/Rx
Optical switch
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WDM WDM WDM WDM treetreetreetree PON experimentsPON experimentsPON experimentsPON experiments
� Transmission experiments at 1 Gbps
� DPSK modulation format
� CO output power: 0 dBm
� Losses
∙ 30 km fiber spool � 5.2 dB
∙ 4 Remote nodes
� 1.6 dB for pass-through
� 13.2 dB for drop
∙ Second distribution stage
� Emulated by means of a VOA
� 21 dB losses to the link � 1:128 splitting ratio
� Overall splitting ratio: 4x2x128=1024 homes
-60
-50
-40
-30
-20
-10
0
0 500 1000 1500 2000
Frequency (MHz)
Po
wer
(d
Bm
)
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Experimental Experimental Experimental Experimental resultsresultsresultsresults
-12
-10
-8
-6
-4
-2
0
-52 -50 -48 -46 -44 -42 -40 -38Pin (dBm)
log(
BE
R)
RN1RN2RN4
40.1 dB41.5 dB40.7 dB-44.2 dBm41.2 dB42.9 dBPowerBudget
39.4 dB41 dB44.2 dB44.2 dB41 dB39.4 dBLink Losses
-40-2 dBm-41.6 dBm-40.8 dBm-44.3 dBm*-41.3 dBm-43 dBmSensitivity
RN4RN2RN1RN4RN2RN1
Resilient modeNormal Operation10-9 (*10-6 )
� BER floor due to phase noise and mixer electronics.
� FEC required for resilience
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ConclusionsConclusionsConclusionsConclusions
� A combined ring-tree access network topology has been demonstrated∙ Flexible, scalable
∙ large number of users (up to 1024102410241024)
∙ Large capacity (more than 1 Tb/s)
∙ completely passive outside plant
∙ wavelength-transparent remote nodes � GPON ODN compatible
� Transmission experiments at 1 Gb/s∙ sensitivity of -43 dBm in RN1, after 30 km
∙ Power budget of 42.9 dB (49 dB at 10Power budget of 42.9 dB (49 dB at 10Power budget of 42.9 dB (49 dB at 10Power budget of 42.9 dB (49 dB at 10----3333))))
∙ 4 GHz channel spacing4 GHz channel spacing4 GHz channel spacing4 GHz channel spacing
∙ FEC is convenient for robutsness.
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AcknowledgementsAcknowledgementsAcknowledgementsAcknowledgements
� Dr.-Ing. Ronald Freund (HHI) � Dr. Carlos Bock (UEssex)
www.tsc.upc.edu/gco