WDM-PON Overview

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  • Always Surpassing Customers ExpectationsLG-Nortel Proprietary Information

    WDM-PON Overview

    2009.9.22

    Chang-Hee Lee

    LG-Nortel and KAIST

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    Content

    2

    > Introduction> Colorless optical sources

    Broadband optical sources Injection seeded reflective modulators Tunable lasers

    > Architectures Protection Broadcasting and Video overlay OTDR Upgrade to 10G Long reach PONs

    > WDM-PON global status> Summary

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    Introduction: why p-t-p network?

    > Trends Bandwidth growth

    10 times every 5 years (Nielsons law, Optical Moores law) Video centric services

    High, bandwidth, high QoS, long connection time Picture and video clip exchange

    Convergence over fiber based optical networks Voice, data, video, and wireless (2G , 3G, LTE) Residential and business

    > Observations Long lifetime of outside plant

    Fiber and passive devices guarantee > 25 years lifetime. TDM-PON

    Ever changing technology: BPON GPON 10 G PON 40 G PON Limited scalability due to high speed transmission over high loss link

    3

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    WDM PON Values

    > Futureproofsolution FutureproofLifetimeOutsidePlantoperation(>25years) GracefulUpgradePathtoFutureHighBandwidthApplications

    >WDMPONscalesdedicatedBWto1G,10Gandbeyond> ImprovedCustomerExperience

    Securesymmetricptpconnection,Nobandwidthsharing Bitrateandprotocoltransparencies Easyprotectionandfaultlocalization

    > LowTotalCostofOwnership LowOPEXcosteffectivelyprovidedbycolorlessONTs Lowupgradecostforfuturehighbandwidthservices Oneinfrastructureforresidentialandbusinessservices Achievedinflectionpointforcomponentindustrializationstart Significant improvementsinWDMandDSPtoimprovereachesaidingincostreduction

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    Colorless optical sources

    > Colorless ONT (ONU) is essential for WDM-PON, since multiple users are connected to a PON.

    > Methods for colorless operation Broadband light sources

    A source that covers spectral range of transmission Suffers slicing losses

    Injection seeding Injection of seed light from a CO to ONT ONT has an reflective modulator Requires seed light

    Tunable lasers A narrow band light tunable over spectral range of transmission Needs prior information of wavelength

    5

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    Broadband Light Sources

    Broadband Light Source

    SMF

    RNCO

    - A simple method

    - Slicing loss > 1/N- Limitation in modulation bandwidth for some sources- Beat noises for an incoherent sources

    . Beat noise can be mitigated with a low noisemulti-wavelength laser (e.g., QD laser).

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    Injection seeded reflective modulators

    Reflective modulator

    SMF

    BLS

    CO RN

    Seeding sources Limiting factors Reflective modulators

    Incoherent light(ASE)

    Source noise F-P LD, RSOA, EA+SOANo restriction on spectral response

    Coherent light(Bank of DFB LDs)

    Reflection noises RSOA, EA+SOARestriction on spectral response

    Downstream signal(incoherent or coherent)

    Source noise/reflection noise Downstream penalty

    Same as above

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    Reduction of Reflection Noises

    Signal

    Upstream signal

    PD TIA

    AfterReceiver

    Reflection noise

    Signal

    PD TIA

    AfterReceiver

    Upstream signal

    Seed light

    November 10, 20098

    Seed light

    Reflection noise

    > Broaden line-width of seed light Broadband seed light, phase modulation,

    > Shift of signal spectrum

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    Tunable laser

    Tunable laser

    SMF

    RNCO

    - No slicing loss- Possibly high modulation bandwidth- Low cost tunable lasers are the ultimate end goal.- Coherent detection can improve link budget and channel counts.

    . Needs coherent tunable laser and DSP

    - Needs prior information for tuning wavelength. End to end control may be complex to mitigate.

    - Cost is very high for access applications.

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    Architecture of WDM-PON

    OLT SwitchOLT

    Metro Core

    S/WGUI

    Cor

    eR

    oute

    r

    L2/L

    3 sw

    itch

    Stre

    am

    Serv

    er

    ONTTVs

    VideoPhonePCs

    Phones

    TVsVideoPhonePCs

    Phones

    TVsVideoPhonePCs

    PhonesHome

    1, 1

    2, 2TRx1TRx2

    TRxn

    TRx3

    BLSA

    3, 3

    n, n

    WirelessAccess Point

    MDU

    xDSL

    BLSB

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    OLT RN

    2 x 2N A

    WG

    BLS(U) BLS(D)

    FaultMonitor

    Fault Monitor

    Fault Monitor

    Fault Monitor

    Fault Monitor

    TRxEthernetSwitch

    TRxEthernetSwitch

    TRx EthernetSwitch

    TRx EthernetSwitch

    ONU 1

    ONU N

    Protection of Fiber Faults

    (a) (b)

    volta

    ge(a

    rbitr

    ary

    units

    )

    NormalFiber failure

    Upstream

    8ms

    Time (ms)20 8040 60 vol

    tage

    (arb

    itrar

    y un

    its)

    NormalFiber failure

    Upstream

    9ms

    Time (ms)20 80 10040 60

    Normal / DF / FF / Both fault (ONU4)Normal / DF / FF / Both fault (ONU8)

    Normal / DF / FF / Both fault (ONU12)

    Switching Time

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    Broadcast/multicast in WDM-PON

    TRx

    EM

    Multicast/RF overlay

    OLT

    BLS BLSAW

    G

    TRx

    TRx

    OA splitter

    #1#2

    #3

    WDM 3

    1N

    RN ONUs

    12

    AW

    G

    ASE orMW Laser

    TRx

    TRx

    TRx

    *EM (External modulator)

    *OA (Optical amplifier)

    2009-11-10

    * Multiple band transmission by using periodic transmission characteristic of AWG

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    Broadcast signal transmission at 1.25 Gb/s channel

    Isolator

    50:50 CouplerF-P LD 1

    Isolator

    F-P LD 2

    Output

    -80

    -70

    -60

    -50

    -40

    -30

    -20

    -10

    0

    1555 1557 1559 1561 1563 1565 1567 1569 1571 1573 1575Wavelength (nm)

    Pow

    er (d

    Bm

    )

    F-P LD@ temp=28.6123456

    78910111213

    14151617

    18192021

    0 0 .5 1 1 .5-150

    -140

    -130

    -120

    -110

    -100

    -90

    -80

    F re q u e n cy (G H z)

    Pow

    er (d

    Bm

    )

    100 GHz filtered ASE100 GHz filtered MI F-P LDs

    100 GHz filtered ASE

    100 GHz filtered MI F-P LDs

    > F-P LD 1, 2 Front facet reflectivity of F-P LD : 0.1 ~0.2 % Laser cavity length : 400 um

    > Passive cavity length : 9 cm

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    Fault localization with tunable OTDR

    ONTCO

    1

    RN

    20 km

    5 km

    CWDM

    TRX

    AW

    G AW

    G

    L-bandBLS 41

    2 3

    PIN-PD

    F-P LD

    Control Unit

    Pulse generator

    Tunable BPF

    Processing Unit

    TunableOTDR

    TRX

    TRX

    TRX

    TRX

    TRX

    TRX

    TRX

    0 5 10 15 20 25 30-90

    -85

    -80

    -75

    -70

    -65

    -60

    -55

    -50

    Distance (km)

    Pow

    er (d

    Bm

    )

    OTDR Trace

    Ch. 10 5 10 15 20 25 30

    -90

    -85

    -80

    -75

    -70

    -65

    -60

    -55

    -50

    Distance (km)

    Pow

    er (d

    Bm

    )

    OTDR Trace

    Ch. 2

    0 5 10 15 20 25 30-90

    -85

    -80

    -75

    -70

    -65

    -60

    -55

    -50

    Distance (km)

    Pow

    er (d

    Bm

    )

    OTDR Trace

    Ch. 30 5 10 15 20 25 30

    -90

    -85

    -80

    -75

    -70

    -65

    -60

    -55

    -50

    Distance (km)

    Pow

    er (d

    Bm

    )

    OTDR Trace

    Ch. 4

    BLS(U) BLS(D)

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    Upgrade to 10 Gb/s

    C/L BLS

    M/CPIN

    F-P LD

    ONT 1

    M/CPIN

    F-P LD

    ONT 32

    M/CPIN

    F-P LD

    ONT K

    M/C F-P LD

    PIN

    32

    M/C F-P LD

    PIN

    1

    M/C F-P LD

    PIN

    K

    20 km

    . . .. . .

    . . .. . .

    Upstream

    Downstream

    OLT RN ONTs

    AW

    G

    AW

    GSmooth migration is available to 10 Gb/s in WDM-PON based on the

    WL F-P LD by changing the transceivers both at OLT and ONT.

    Tunablelaser

    Controller

    PD

    Controller

    PD

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    Measured wavelength tracking characteristic

    1544

    1546

    1548

    1550

    1552

    1554

    1556

    1558

    1560

    1562

    0 10 20 30 40 50 60

    Wav

    elen

    gth

    [nm

    ]

    Time [minute]

    Self wavelength tracking

    Wavelength deviation from the target wavelength was 0.05 nm with Gaussian AWG and 0.