self coherent detection & reflective modulation for optical access networks (ftth )
DESCRIPTION
Acknowledgement: Piano+ EU Multi-National Program: Project O T O N E S (8 academic + industrial partners in Israel, Germany & UK ) also funded by the Israeli Chief Scientist Office. Self Coherent Detection & Reflective Modulation for Optical Access Networks (FTTH ). - PowerPoint PPT PresentationTRANSCRIPT
Self Coherent Detection &Reflective Modulation for
Optical Access Networks (FTTH)
Amos Agmon, Moshe NazarathyTechnion, Israel Institute of Technology
Talk given at Optical Engineering 2014Netanya, Israel
Acknowledgement: Piano+ EU Multi-National Program:Project OTONES (8 academic + industrial partners in Israel, Germany & UK )
also funded by the Israeli Chief Scientist Office
Outline
• Motivation and system design guidelines• Introduction: Optical Detection and
Motivation to Self-coherent detection• Reflective Modulation• Combining Down-Stream(DS) & Up-stream
(US)• OTONES Network design• Conclusions
2
Power dissipation of Information and Communication Equipment*
3
Shared Network Equipment~ 1 W/user
Access Network andHome Gateway:~ 10 W/user
Home Devices:~ 100 W/user
Customer Premises
* Interview with P. Vetter, Bell Labs, Sep-2010, http://www.youtube.com/watch?v=-M-9v7OdtFY
Motivation & Design Guidelines• Access Networks required to increase data throughputs
while reducing power dissipation• Designing an access-network (FTTH) allowing for low-
complexity, power-efficient Optical Network Units (ONU=Customer Premises Equipment)– Laserless, colorless low complexity ONUs– Low rate signal processing– ≥1 Gbps ONU peak Down-Stream (DS) throughput– FSAN Class B+ ODN (29 dB loss budget per Optical Distribution
Network (ODN))– Split ratio ≥ 1:64
4
5
Intro. : Optical Transmission
6
( )Id t
( )Qd t
c
( )ID
2W
c
( )QjD
2W
c
( ( ))
( )I QDjD
D
2W
0
( )
( ) ( )I Q
D
D jD
W
@ c
90 0
MZM I
MZM Q
CW Laser
doubling data throughputby means of simultaneous transmission of I & Q
Intro. : Optical Detection
7
( )Id t
( )Qd t
cos 2 ct
sin 2 ct
( )Id t
( )Qd t@ c
90 0
MZM I
MZM Q
CW Laser
LPF
LPF
Intro. : Optical Detection
8
PD
( )i t
@ c
90 0
MZM I
MZM Q
CW Laser
= LPF 2
( )Qd t
( )Id t
Intro. : Optical Detection
9
22( ) ( ) 2 Re ( ) ( )( ) LP LPcj ts t h t s t e h ti t
2*
22 * *2 2
1 12 ( ) ( ) ( )2 2
1 ( ) ( ) 2 ( ) ( ) ( )2
LP
LP
c c
c c c c
j t j t
j t j t j t j t
s t e s t e h t
s t e s t e s t e s t e h t
2( ) ( )i t s t
( )s t ( )s t
( )S
W
= LPF 2( )i t ( )i t
0
( ) ( )
( )QID jD
D
W
Intro. : Limits of Direct Detection
10
( )Qd t
2( ) ( )i t d t
( )Id t
2( )Id t
2( )Qd t
( )Q tj d
2( )Id t
0
2W
0 2W
Undetectable I-Q Mixture
2( ) ( )i t d t
PD@ c
90 0
MZM I
MZM Q
CW Laser
Solution: Coherent (heterodyne) Det.
11
( )Qd t
PD
( )Id t
2( ) ( )i t s t
c IFf c
( )S
0
( )D
W
0IFf
( )( ) ( )IFS D fL
2( ) ( )i t s t
2( ) IFj tL d t e
2L
LO
0 IFfWWIFf
2( )d t
22 2 Re (( )) IFj td ed tL tL
* ( ) IFj tL d t e 2Re
@ c
90 0
MZM I
MZM Q
CW Laser
c IFf LO
EXPENSIVE
SOLUTION
Coherent Det. drawbacks
• Complex and expensive: Tunable laser required
• Prone to frequency drifts and Phase noise, highly stable lasers required for large constellations
• Phase noise is enhanced by EqualizationCurrently, Coherent Det. is prohibitive for mass deployed communication links
12
Self Coherent Tx
13
LO mixed at Tx output:
0IFf
( ) ( )IFS D f
( )L
@ cCW
I-Q MZM
CW @ c IFf
3dB coupler locked pair
Tx
2( ) IFj tL d t e
Self Coherent Advantages
• Reduced Rx complexity: Single Photo-Diode, Laserless, colorless
• Tx Remains simple: Generating a locked pair is not hard
• Phase noise immunity: Both for Laser PN & Non-linear Self Phase Modulation (SPM)!
14
2( ) ( )i t s t
( ) ( )j t j te e
2L 2( )d t
22 ( ) ( )( ) 2 Re ( ) IF j jj t t tL d t L d t e e e
*( ) ( )2Re ( ) IFjj t jt teL d t e e PN canceled out!
Self Coherent - Summary
• Spectral efficiency of Coherent Detection• Allows for Linear equalization (CD, PMD
mitigation)• Laser coherency (Linewidth) does not effect Rx
performance→ Low quality laser may be used• Simple Tx & Rx
15
Up-Stream: Reflective Modulation forLaserless Optical Network Unit (ONU)
16
DS Self Coh. Rx
US Tx
ONU
US Carriersource
3 dB coupler
US Tx
Self Coh. Tx
US Rx
Uni-directional Reflective Modulation
17
c W 2c W 3c W c
P
W 2W 3W0
Ue
U
c W 2c W 3c W c
Reflective TxtoRx
I-Q MZM
PBSXy
900
pol rot( )Iu t
( )Qu t
USDS
Bi-directional Reflective Modulation
18
W 2W 3W0
Ue
DP
c W 2c W 3c W c
U UxD
c W 2c W 3c W c
D+RBSP+RBS
c W 2c W 3c W cReflective Tx
toRx
I-Q MZM
PBSXy
900
pol rot( )Iu t
( )Qu t
USDS
Bi-directional Reflective Modulation
19
W 2W 3W0
Ue
DP
c W 2c W 3c W c 4c W
OpticalSSB
Reflective TxtoRx
I-Q MZM
PBSXy
900
pol rot( )Iu t
( )Qu t
USDS U UxD
c W 2c W 3c W c 4c W
c W 2c W 3c W c 4c W
URBS UxDRBS
Pslot
Uslot
Dslot
Gslot
PUDG pattern
OTONES network
• A new bi-directional access network designed from the ground up at the system, sub-system and component levels– low-cost– power-efficient– long-reach– spectral-efficiency
• Applying Self-coherent det. & reflective modulation• 1 Gbps (peak) per user, low rate ADC (<500 MSamp/s)• Total Throughput:
– Class I: 10G/10G over 12.5 GHz – 40 dB reach - lowest-cost– Class II: 20G/20G over 25 GHz – 38.5 dB reach - mid-cost– Class III: 40G/40G over 50 GHz – 35 dB reach - highest cost
20
Remote HU
BRem
ote HUB1 N
1:64Passivesplitter
(De)IL(De)IL
WDMWDM
RemoteNODES
ONU64
ONU2
ONU1
ONU64
ONU2
ONU1
OLT
Feederfiber
DS
US
DS Tx-s
US Rx-s
21N
21N
ODN
12.GHz-off-grid WDM
ODN
@OLT: US Symbol SNR=18.5 dB
@ONUDS Symbol
SNR=18.5 dB
/
8DSPdBm
11 (37 )dB Km
(min Symbol SNR for 16QAM=16.5 dB)
↓(a)↑(e)
↓(b)
1 2
↑(c)
WDM
WDM
EDFAs+Circulators
US OSNR@ Photo-Diode=19 dB
DS OSNR = 17.1 dB
Pslot
Uslot
Dslot
Gslot
Pslot
Uslot
Dslot
Gslot
@ O
LT
@ H
UB
f
25 GHz DS OFDM SPECTRUM
DS
DS
(a)
(b)
seed
seed
SPECTRAL DESIGN
SLICE 2
SLICE 1
ON
U R
x DS optical signal@ONU PD
Plantarchitecture ofOTONESlong-reachPON:
11 dBfeederfiber
optical filtering+OA
Class B+ ODNs:29 dB
Loss budget
11 dB feeder+ 29 dB ODN=40 dB loss budget(Class I)
Backward-compatible w/ existing ODN PON Plantand may even co-exist with (X)GPON, TWDM, etc. 21
OTONES ONU
90 degPOL.ROT.
Si PIC
Y
X-POL(rotatedY-POL)
OTONES ONU
Var.SPLIT
Q I
SOA
X
SMF FIBER IN/OUT
X-POL
DiscreteOpticalComp.
PBS
Y-POLRx
X-POLRxTIA TIA
TRANSCEIVER DSP
SSBMod.
Packet SW.+ User I/F ONUASIC
analogdigital
OF
IQ MODBi-Directional
Postamp.
LPF
Postamp.
LPF
Drvamp
I-ADC Q-ADC I-ADC Q-ADCI-DAC Q-DAC
Drvamp
10nm thin-film OBPF
VGA VGAVar.GainAmp.
PD PD
Data in/out
Signal here contains asingle-slice
A patent app was filed early in 2010
X-POLREMODY-POLREMOD
22
MIXED-SIGNAL ASIC
thin-film optical filteridentical for all ONUs“colorless” ONU !(no tunable or variableparameters filter in ONU)
Laserless reflective ONU !US re-mod of DS lightby coherent 16-QAMidentical on both X,Y polarizations
Pslot
Uslot
Dslot
Gslot
Pslot
Uslot
Dslot
Gslot
@ O
LT
@Re
mot
e- H
UB
ON
U T
x
MO
D=MIXER
@ R
emot
e-HU
B@
OLT
P U D G P U D G
DS
repe
at
f
25 GHz DS OFDM SPECTRUM
Electricalmodulation signal (US OFDM Info)
DS optical signal @ ONU INPUT to IQ US Modulator
Light @ IQ Mod OUT(re-modulated US)
DS
DS
US
US
(a)
(b)
(c)
(d)
(e)
(a)
seed
seed
SPECTRAL DESIGN
SLICE 2
SLICE 1 filter profile
remodulation
US
DS
SLICE 1
SLICE 1 SLICE 2O
NU
Rx DS optical signal
@ONU PD
X
90 degPOL.ROT.
Si PIC
Y
X-POL(rotatedY-POL)
OTONES ONU
Var.SPLIT
Q I
SOA
X
SMF FIBER IN/OUT
X-POL
DiscreteOpticalComp.
PBS
Y-POLRx
X-POLRxTIA TIA
TRANSCEIVER DSP
SSBMod.
Packet SW.+ User I/F ONUASIC
analogdigital
OF
IQ MODBi-Directional
Postamp.
LPF
Postamp.
LPF
Drvamp
I-ADC Q-ADC I-ADC Q-ADCI-DAC Q-DAC
Drvamp
10nm thin-film OBPF, identical for all ONUs
(practically “colorless”)
VGA VGAVar.GainAmp.
PD PD
Data in/out
Signal here contains asingle-slice
23
ADC/DAC: 156 MHz 417MS/s
narrowband filter anddetect just one stream
ENERGY EFFICIENT
MIXED-SIGNALONU ASIC
Spectral Design
elD U
eln nnD U
elP U
P U
P D
elU
U
DSDET
OTONES simulation resultsDS @ OLT output
DS @Remote Hub output, RHS slice filtered down
ONU PD output, electrical
P DD D
P P2P D
US @ OLT input
eln nnD U
desiredremodspurious
ONU DS 16-QAM constellation after max-ratio polarization-diversity combining
SNR=18.5 dB
OLT US16-QAM constellation after max-ratio polarization-diversity combining
SNR=18.5 dB
24
Ideal 16-QAM SNR=16.5 dB at BER=10-3 2 dB margin
• Bi-directional Network simulation using a Matlab-Simulink Model were performed at the Technion
• ONU Photonic Integrated Circuit (PIC) – Developed at Karlsruhe Institute of Technology (KIT), Germany, Expected May-’14
• ONU Digital Rx implemented at Technion-IIT, on a Xilinx Virtex-6 chip
• OLT Digital Rx, Optical SSB modulator – Implemented at Technion-IIT, expected during Apr-’14
• Proof of concept experiments – planned during Q2 ‘14
OTONES Network Prototype is currently under implementation
25PIC mask – courtesy of Philipp Schindler, KIT, Germany
Conclusions
• Self Coherent Detection – Cost effective scheme for spectral efficient low cost optical links
• Reflective Modulation – Cost effective scheme for bi-directional transmission in access networks
• Both techniques may be applied in future optical access networks (FTTH)
26
that’s it
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