Low Cost Transceiver For Ultra Dense WDM Access Networks

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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

ers

itat

Politè

cnic

ade C

ata

lunya

Low Cost Homodyne Transceiver Low Cost Homodyne Transceiver

for Ultrafor Ultra--Dense WDM Access Dense WDM Access

NetworksNetworks

Josep MJosep MJosep MJosep Mªªªª FFFFààààbregabregabregabrega and Josep Pratand Josep Pratand Josep Pratand Josep [email protected]


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OutlineOutlineOutlineOutline

� Introduction

� Receiver Performances

∙ Phase Noise

∙ Channel spacing

� Case study: WDM tree PON

� Conclusions


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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 GHz

[1] C.-H. Lee, et al., J. Lightwave Technol., vol. 24, no. 12, pp. 4568-4583, Dec. 2006.


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∙ IM-DD systems limited

� Sensitivity

�Optical filters selectivity

∙ Coherent systems

�Heterodyne

– Image frequency problems

�Homodyne

– Phase locking problems LocalLaser

+

-

+

-OpticalInput Ip(t)


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Locallaser

+

-

Data and Phase

recovery

PM

Data

DataReceiver

TransceiverPSK Downstream


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� Introduction

� ReceiverReceiverReceiverReceiver PerformancesPerformancesPerformancesPerformances

∙ Phase Noise

∙ Channel spacing


� Conclusions


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TimeTimeTimeTime----SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver

Laser

CLKRecovery

+

-

PhaseScrambler

Tb

Tb

Tb/2

Data out

OpticalInput

I’

Q’

Vout

+

I’

Q’

outV

[2] J. Prat and J. M. Fabrega, ECOC 2005, Glasgow, Scotland, sept. 2005, paper We.P.104

0º

90º


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Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver

� Diversity achieved by switching local laser phase [1]

� Achieved high tolerance to laser linewidth with simple architecture [2] and narrow channel spacing [3]

� 3 dB penalty with respect to an ideal homodynesystem due to the phase switching

� Similar structure has been integrated on a chip [4]

I Q

t0 t0+T/2 t0+Tt

I Q

t0+3T/2 t0+2T

[2] J. Prat and J. M. Fabrega, ECOC 2005, Glasgow, Scotland, sept. 2005, paper We.P.104 [3] J. M. Fabrega and J. Prat, OSA Optics Letters, vol. 32, no. 5, March 2007[4] J. M. Fabrega and J. Prat, OSA Optics Letters, vol. 34, no. 4, February 2009[5] J. Klamkin, et al., in Proceedings LEOS 2007, pp. 40-41


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-1

-0,5

0

0,5

1

-1 -0,5 0 0,5 1-1

-0,5

0

0,5

1

-1 -0,5 0 0,5 1

( ) ( ) ( ) ( )

( ) ( )

2 2 2 2 31 2

2 1 31 2 1 2 1 3

1 2

( ) ( )( ) ( )( ) ' ( ) ' 1 sin sin

2 2

( ) ( )1cos 2 ( ) 2cos ( ) ( ) sin sin ( ) ( ) sin ( ) ( )

2 2

1sin 2 ( ) 2sin ( ) ( ) sin

2

out b

e

e

t tt tV C d t d t T

t tt t t t t t t

t t t

φ φφ φ

φ φφ φ φ φ φ φ φ

φ φ φ

∆ + ∆ ∆ + ∆ = − − − +

∆ + ∆ + ∆ + ∆ + ∆ + ∆ ∆ + ∆ +

+ ∆ + ∆ ( ) ( )2 1 31 2 1 3

( ) ( )cos ( ) ( ) sin ( ) ( )

2

t tt t t t

φ φ φ φ φ φ ∆ + ∆ − ∆ + ∆ ∆ + ∆

1( ) ( )

2b

e e

Tt t tφ φ φ ∆ = − −

( )2 ( )

2b

e e b

Tt t t Tφ φ φ ∆ = − − −

( )3

3( )

2b

e b e

Tt t T tφ φ φ ∆ = − − −


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Laser

CLKRecovery

+

-

PhaseScrambler

Tb

Data out

ES(t)

Tb/2ELO(t)

IP(t) I f(t)

Post-Processing

Vout


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� Introduction


∙ PhasePhasePhasePhase NoiseNoiseNoiseNoise

∙ Channel spacing


� Conclusions


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PhasePhasePhasePhase NoiseNoiseNoiseNoise: Experimental : Experimental : Experimental : Experimental SetupSetupSetupSetup

PRBS

CW Laser 1

-

Balancedreceiver

PM

CLK

fiberMZM

0º-180º

0º-90º

ElectricalprocessingOSC

ESA

CW Laser 2

TX

LO

-60

-50

-40

-30

-20

-10

0

0 500 1000 1500 2000

Frequency (MHz)

Pow

er (

dBm

)

Bit rate fixed at 1 Gbps

Data DPSK modulated

CW Laser 1: External Cavity laser @ 100 kHz Linewidth

CW Laser 2: Standard DFB Laser @ 1-30 MHz Linewidth


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PhasePhasePhasePhase NoiseNoiseNoiseNoise: : : : ResultsResultsResultsResults

� High sensitivity:

∙ -38 dBm sensitivity @ BER 10-9

� High phase noise tolerance:

∙ 18 MHz Linewidth tolerance @ BER 10-3

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0 5 10 15 20 25 30 35 40 45 50

Total laser linewidth (MHz)

log(

BE

R)

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-2

-46 -45 -44 -43 -42 -41 -40 -39 -38

Input power (dBm)

log(

BE

R)


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� Introduction


∙ Phase Noise

∙ ChannelChannelChannelChannel spacingspacingspacingspacing


� Conclusions


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ChannelChannelChannelChannel SpacingSpacingSpacingSpacing: Experimental : Experimental : Experimental : Experimental SetupSetupSetupSetup

PRBS

CW Laser 1

--

Balancedreceiver

PM

CLK

27 kmfiber

0º-180º

0º-90º

Electricalprocessing

OSC

ESA

CW Laser 2

INT

LO

PM

MZM0º-180º

PRBS

CW Laser 3

TX

Bit rate fixed at 1 Gbps

Data DPSK modulated

CW Laser 1-3: External Cavity laser @ 100 kHz Linewidth


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ChannelChannelChannelChannel SpacingSpacingSpacingSpacing: : : : ResultsResultsResultsResults

0

2

4

6

8

10

0 1 2 3 4 5 6

Channel spacing (GHz)

Pen

alty

(dB

)

Numericalmodel

Ideal system

� 1 dB penalty @ 3 GHz channel spacing

� 3 dB penalty @ <2 GHz channel spacing


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� Introduction


∙ Phase Noise

∙ Channel spacing

� CaseCaseCaseCase studystudystudystudy: WDM : WDM : WDM : WDM treetreetreetree PONPONPONPON

� Conclusions


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CaseCaseCaseCase studystudystudystudy: WDM : WDM : WDM : WDM treetreetreetree PONPONPONPON

Laser

CLKRecovery

PhaseModulator

Tb

Data out

Tb/2MZM

Data in

0º-180º

Optical

Output

Optical

Input

D-WDM MUX

(RN 1)

CO

power splitter(RN 2)

λ1 .. λN D-WDM bands

Nx PONs

λ1 D-WDM band

λN D-W

DM band

K UD-WDM channels

D-WDM band

CPE

CPE

CPE

CPE

CPE

CPE

K users


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WDM WDM WDM WDM treetreetreetree PON experimentsPON experimentsPON experimentsPON experiments

� Transmission experiments at 1 Gbps

� DPSK modulation format

� 40x32 = 1280 users � > 1 Tbps

� Outside plant losses

∙ AWG 1x40 IL = 6.47dB

∙ 1:32 power splitter IL = 16dB

∙ 25km SMF span IL = 5.2dB

� –38.7 dBm sensitivity @ BER 10-10


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WDM WDM WDM WDM treetreetreetree PON experimentsPON experimentsPON experimentsPON experiments

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-48 -46 -44 -42 -40 -38 -36

Input power (dBm)

log(

BE

R)

Downstream

Upstream


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� Introduction


∙ Phase Noise

∙ Channel spacing


� ConclusionsConclusionsConclusionsConclusions


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ConclusionsConclusionsConclusionsConclusions

� A new homodyne receiver was discussed and demonstrated.

� Ideal for a λTTU environment

� Sensitivity of -38 dBm for a BER 10-9, at 1 Gbps

� Linewidth tolerance of 18 MHz linewidth. ∙ FEC codes must be used

� Minimum channel spacing of 3 GHz @ 1 Gbps

� Pure WDM-Tree PON results reported∙ -38.7 dBm sensitivity @ 1 Gbps

� The architecture proposed is fully integrable

� Homodyne reception is a feasible way to enable UD-WDM PONs in a near future.


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-- --G

CO

GC

OG

CO

GC

O

Universitat Politècnica de Catalunya (UPC)Dept. of Signal Theory and Communications (TSC)

Optical Communications Group (GCO)www.tsc.upc.edu/gco

Univ

ers

itat

Politè

cnic

ade C

ata

lunya

ThanksThanks!!!!

Josep MJosep MJosep MJosep Mªªªª FFFFàààà[email protected]

Technology

Low Cost Transceiver For Ultra Dense WDM Access Networks