Advances in Optoelectronic Technologies for ROADM Subsystem s Louay - - PowerPoint PPT Presentation

Advances in Optoelectronic Technologies for ROADM Subsystem s

Louay Eldada Chief Technology Officer DuPont Photonics Technologies

louay.eldada@usa.dupont.com http://www.photonics.dupont.com

2

Use of ROADM in Optical Networks

OXC ROADM DEMUX SPLI TTER METRO ACCESS FTTP Consumer LONG HAUL

Backbone Network Feeder Ring Network Distribution Network Core Metro Long Haul Access Access Access

ROADM Used for Add/Drop (1x5, 1x9, 1x11) ROADM Used for Connectivity (1x4, 1x8) Optical Switch (OXC)

3

Migration Toward Agile Optical Networks

External-cavity laser Drop-in for fixed transponder I nventory system sim plification Full-band tunable laser λ blocker + fixed filters

• r Dem ux/ Sw itch/ Mux

PLC Dual-use as DGE Stranded capacity reduction, sim ple engineering rules Type I ROADM Lim ited flexibility Tunable filters/ lasers

• r OXC
• r W SS

Retain blocker, add tunable laser, no im pact to thru path; or all PLC solution, can be m ore cost-effective; or W SS No m anual intervention, m onitor & control Type I I ROADM Any λ to any port Degree 2 W SS Select locations only; interop w ith other nodes, sam e lasers Ring-interconnect w / o OEO Higher-Degree ROADM Any com bination of λ’s to any port Large W SS Select locations only Mesh protection, etc. Optical Sw itch ( aka OXC) I ntegrated m anagem ent Sam e physical layer hardw are Optim um utilization Minim um OpEx Autonom ous Agility Therm al-tuned DFB Drop-in for fixed laser I nventory reduction Narrow tunable laser Fixed DW DM lasers, Fixed OADM Fixed functions

New Com ponents Com patibility Justification Netw ork Function

Optoelectronic functions needed in agile optical networks:

• Tunable Lasers
• ROADMs

RHK (partial)

4

ROADM Use in Networks

Cisco, Tellabs, Hitachi JDSU, DuPont, OpTun, Chromux, Neophotonics, NEL Metro (Demux/Switch/Mux) JDSU, DuPont, CoAdna, Engana, Metconnex, LichtConnect, Capella Avanex, JDSU, DuPont, LightConnect, CoAdna, Polycromix, Xtellus Avanex, JDSU, DuPont, LightConnect

Com ponent Vendors

Fujitsu, Meriton Metro (WSS) Verizon, MCI, SBC (Alcatel/Tropic), BellSouth (Tellabs), NTT Comcast, Cox , Brighthouse (Fujitsu), Shaw Alcatel/Tropic, Lucent Metro (Wavelength Blocker) Qwest (Lucent), Verizon (Lucent), GigBE project (Ciena), MCI (Ciena), BT (Marconi), MCI (Siemens), AT&T (Siemens), Broadwing (Corvis) Lucent, Ciena, Marconi, Siemens Long-Haul (Wavelength Blocker)

Carriers

(System Suppliers)

System Vendors Market

(Technology)

About 700 ROADM nodes were deployed in 2004, mostly in the second half of the year. The majority of these nodes were 32-channel systems from Fujitsu and Cisco, with the largest deployments being in Japan and North America.

RHK (partial)

5

ROADM path lags tunable laser by 2 years

Blocker + Tunable Filters/Lasers skipped? Wavelength Selective Switch expected

Fixed Narrow (~8 ch) Moderate (~20 ch) Wide (~40 ch)

Source:RHK

laser laser

2003 2004 2005 Fixed “Type I” Higher degree “Type II”

Laser ROADM ROADM ROADM Integrated Demux/ Switch/Mux

“over 1000 shipped”

• JDSU

12/01/04

6

ROADM Types

Blocker as DGE

EDFA Blocker Tunable Filters/Rx Tunable

Lasers

Type II

Splitter Combiner Blocker Blocker Splitter Combiner Tunable Filters/Rx Tunable Lasers Blocker

Higher-Degree ROADM Type I

Fixed Filters Blocker Splitter Combiner λ λ λ λ Fixed Lasers λ λ λ λ

Type II

OXC OXC

Type I Higher-Degree ROADM

Wavelength-Blocker-Based Broadcast and Select Integrated Demux/Switch/Mux

Type II or Higher-Degree ROADM

Wavelength Selective Switch Splitter Tunable Filters/Rx Combiner Tunable Lasers

LC- or MEMS-Based WSS

7

Wavelength-Blocker-Based Type I ROADM

Splitter Transm itters

ADD

Splitter 1 xN ( or 1 xM) Splitter

DROP

Receivers OPM W avelength Blocker

. . .

Dem ux M u x

… … … …

Nx1 ( or Mx1 ) Com biner

… …

Tunable Filters

1 N 2

. . .

Common Characteristics:

• Free-space (MEMS, LC)
• For full reconfigurability:

Tunable lasers at ADD New Gen:

• Splitters/Combiners

replaced with Demux/Mux

• No tunable filters at DROP

Old Generation: Splitters at Drop, Combiners at Add

Add Channels

1 N 2

. . .

M u x Dem ux

. . .

Dem ux

Drop Channels

M u x

. . .

OPM

W avelength Blocker

in

• ut

3 0 % / 7 0 % Splitter 3 0 % / 7 0 % Splitter

New Generation: Demux at Drop, Mux at Add

8

PLC-Based Type I ROADM

λ1 λ2 . . . λ32 IN OUT λ1 λ32 ADD

Control Electronics Power, Data

M U X D E M U X

5% Tap

. . . . . . . . .

λ1 λ2 . . . λ32 IN DROP λ1

D E M U X

15%Tap

λ32 OUT λ1 λ32

Note: Both express and “Add” channels are balanced w ith the built-in VOA array

9

Type II ROADM Configurations

• Free-space, MEMS, LC
• Higher IL ▼
• Difficult to upgrade ▼
• Reliability issues ▼
• Tunable filters at DROP ▼
• For full reconfigurability:

Tunable lasers at ADD ▼

• Large component count ▼
• Expensive ▼
• Can be single PLC ▲
• Lower IL ▲
• Easy to upgrade ▲
• NxM & MxN at A/D give

full reconfigurability ▲

• Integration-friendly ▲
• Small component count ▲
• Low cost ▲

W B-Based Broadcast and Select

Full N (or M of N) Reconfigurability

Splitter Tunable Transm itters

ADD

Splitter 1 xN ( or 1 xM) Splitter

DROP

Receivers OCM W avelength Blocker

. . .

Dem ux M u x

… … … …

Nx1 ( or Mx1 ) Com biner

… …

Tunable Filters

PLC-Based Dem ux/ Sw itch/ Mux

Typical Today: N = 8 , 1 6 , 3 2 , 4 0 M = 4 , 8

Dem ux

ADD DROP

. . . . . . . . . . . . . . . . . .

Transm itters Receivers Mux OCM DCE DCE OCM 1 x2 2 x1

MxN OXC NxM OXC

10

λ1 λ2 . . . λ32 IN OUT λ1 λ32 ADD DROP λ1 λ32

Control Electronics

Power, Data

M U X D E M U X D E M U X

15%Tap

5% Tap

. . . . . . . . .

Transm itters Receivers

8 x3 2 OXC 3 2 x8 OXC

PLC-Based Type II ROADM

11

Each 8x8 Switch is 112 1x2 Switches → 2 8 8 Elementary Functions Polym er PLC includes 16 1x2 Switches 16 VOA’s 16 Taps 16 Photodiodes 2 8x8 Switches 66 Functions

Fiber 1 I n W est Fiber 2 Out W est Drop 1 − 8 From W est 1 8 1 8

W est Chip

Fiber 2 I n East Fiber 1 Out East

MUX

8 1

East Chip

Add 1 − 8 To W est 1 8 Add 1 − 8 To East Drop 1 − 8 From East

DEMUX 8 x8 OXC

8 1 8 1

MUX

1 8 8 1

DEMUX

1x2 Switch Power Tap Photodiode VOA

8 x8 OXC 8 x8 OXC 8 x8 OXC

Demux/Switch/Mux Type II ROADM

Fully Reconfigurable East/West Separated Architecture

8 λ / Fiber Drop any λ to any port Add any λ from any port

12

7 0 / 3 0 coupler 1 8 2 D M u x M u x D M u x 1 8 2 Sw itch/ VOA Control Electronics 8 x8 Sw itch 8 x8 Sw itch Optional Tap/ PD

I n ( East) Out ( East) Out ( W est) I n ( W est) DROP ( East) ADD ( W est)

Note: Mux and Dem ux are based on thin film filters

Fully Reconfigurable PLC-Based 8-Channel Demux/Switch/Mux Type II ROADM

13

Node Cascading Simulation Layout

Cascade of 16 ROADM nodes (32 AWG’s)

1 6 iterations

Simulation tools and assumptions:

–Rsoft OPTSIM simulation tool is used –Measured spectral IL and CD of Flat Top AWG filters are used –Two optical amplifiers are used at each node –Worst case narrowing

• f ROADM passband

due to temperature variation and center frequency inaccuracy of AWG filters is used

14

Bandwidth of Cascading AWG Filters

Concatenation of Flat-Top AWG Filters y = 79.131x-0.252 y = 50.271x-0.2521

10 20 30 40 50 60 70 80 90 5 10 15 20 25 30 35 Number of Flat-Top AWG Filters Bandwidth (GHz)

3-dB BW (GHz) 0.5-dB BW(GHz) Power (3-dB BW (GHz)) Power (0.5-dB BW(GHz))

15

Simulation Conditions (16 Nodes)

194.0050 194.0050 194.0000 194.0000 Dem ux filter 3 -dB center ( THz) 194.0111 194.0111 194.0111 194.0000 Laser center frequency( THz) 20.0 193.9950 Run4 10.0 193.9950 Run3 10.0 194.0000 Run2 10.0 194.0000 Run1 ROADM Total Loss ( dB) Mux filter 3 -dB center ( THz) Run 1 Run 2 Run 3 Run 4

16

• DuPont PLC ROADM meets

bandwidth requirements for 16-node DWDM rings

– Bandwidth at 0.5dB is over 40 GHz for each ROADM – Bandwidth at 0.5dB is over 20 GHz after 16 cascading nodes (32 AWG’s)

• DuPont PLC ROADM allows use of

low cost, low accuracy lasers for 16- node rings

– Bit error rate (BER) lower than 10-17 – Lasers with +/-10 shift of center frequency can be used without any system performance degradation after 16 cascading nodes

Cascading Simulation Conclusions

1.70E+01 1.75E+01 1.80E+01 1.85E+01 1.90E+01 1.95E+01 2.00E+01 2.05E+01 2.10E+01 193.980 193.990 194.000 194.010 194.020 Laser Center Frequency (THz) Q Value 1.00E-25 1.00E-23 1.00E-21 1.00E-19 1.00E-17 1.00E-15 1.00E-13 193.980 193.990 194.000 194.010 194.020 Laser Center Frequency (THz) BER

17

Comparison of PLC and λ Blocker Approaches for ROADM

$X $X/2

Cost

Low – manual assembly High – automated manufacturing

Potential for Cost Reduction

Free space optics Solid state optics (waveguides)

Technology Platform

< 100 GHz ≥ 100 GHz

Channel Spacing

> 40 ≤ 40

Number of Channels

< 0.3 dB < 0.3 dB

Passband Ripple

< 0.5 dB < 0.5 dB

PDL (in-out) at min attenuation

< 50 ms < 10 ms

Add/Drop Time delay

Four slots Two slots

Size

Average Excellent

Stability and Reliability

< 10 dB < 10 dB

Insertion Loss (in-Drop)

< 13 dB < 10 dB

Insertion Loss (Add-out)

< 11 dB < 12 dB

Insertion Loss (in-out) λ Blocker ROADM PLC ROADM Param eter

18 Any num ber of λ1 - n Any num ber of λ1 - n

D8 DEMUX 1 MUX 2 n MUX MUX MUX MUXMUX MUX MUX I n MUX Out D1 D2 D3 D4 D5 D6 D7 1 xN sw itches λ1 ,λ2 ,…., λn-1 , λn

Any num ber of λ1 - n Any num ber of λ1 - n Any num ber of λ1 - n Any num ber of λ1 - n Any num ber of λ1 - n Any num ber of λ1 - n Any num ber of λ1 - n

Shared bulk grating for all Mux’s and Demux’s

Liquid Crystal & MEMS Based WSS

JDSU

19

Advantages of LC vs MEMS WSS

• Mature components and proven technology (same

technology as wavelength blockers in commercial use)

• Lower cost (simpler alignment and calibration, high yield)
• No notches between channels (for higher cascadability

and upgradability to smaller channel spacing)

• Higher reliability (no moving parts)
• No vibration sensitivity issues
• No sticking and static damage issues
• Telcordia qualified technology platform
• Lower design and supply risk

20

Typical Interleaved Channel Spectra at Drop Port

Performance of 1x4 Liquid Crystal WSS

21

Spectra at Different Attenuation Levels

Performance of 1x4 Liquid Crystal WSS

22

Use in Mesh Networks

Optical Crossconnects

Networks today are not simple ring or mesh, they increasingly include:

• Ring-mesh hybrids
• Stacked rings

Reconfigurable mesh network made up of two interconnected sub-networks, each being an island of transparency

OEO Switch OEO Switch OXC at Degree 8 Node

23

Use in Mesh Networks

Optical Crossconnects

OXC’s are particularly useful in reconfigurable mesh networks where nodes have to route traffic from different directions

Important criteria:

• Non-blocking reconfigurable node
• Reliable configuration (several medium size switch matrices)
• Optical properties (IL, XT, etc.)
• No regeneration, no wavelength conversion

For N fibers (degree N node) and M wavelengths per fiber, M NxN switches are needed

Degree 4 Node for Meshed Architecture 4 Fibers → 4x4 Switches 4 λ / Fiber → 4 Switches

From Local Node To Local Node

Eurescom P615

24

Enabling PLC Technologies

Planar "Free Space" Coupler Waveguide Delay Lines Dummy Guides Inputs Outputs 1 2 N 1 2 N

. . . . . . . .

∆L = constant

• Polymer Based Integrated Switch-VOA Arrays

– Add Switch(2x1)/VOA & OXC(8x8, 32x8) – Low Loss, Low PDL – Low power consumption – Wavelength independence – Telcordia qualified

• Silica Based AWG (Mux/Demux)

– Flat top – Low loss – Low CD – Low PDL – Tight center frequency accuracy ( 5 GHz) – Wide bandwidth ( 80 GHz at 3 dB) – Telcordia qualified

25 40ch Fiber Array Silica AW G Polym er PLC VOA Array

Chip-to-Chip Integration

Chip-to-Chip integration:

• Eliminates fiber arrays, reducing cost
• Eliminates space needed for fiber ribbons and splices
• Eliminates excess loss due to pigtailing
• Improves reliability due to reduced number of interfaces

Example: 40ch VMUX Measured chip-to-chip excess loss: <0.1dB

Silica-on-Si AW G

Polym er Arrays of Sw itches/ VOA’s/ Pow er Monitors 8 x3 2 OXC 3 2 x8 OXC

Silica-on-Si AW G Silica-on-Si AW G

3 2 x8 OXC 8 x3 2 OXC

Silica-on-Si AW G 8ch fiber array 8ch fiber array fiber fiber fiber fiber 8ch fiber array 8ch fiber array

26

Dynamic IC Fabrication

Blank W afer to Diced Chips in 6 Hours

ROAD™

Form 3 : Black box w ith optical and electrical connectors Form 2 : Packaged chip on PCB w ith control electronics and firm w are Polym er W aveguide Fabrication Metalization Form 1 : Packaged chip Dicing, Packaging

27

Cycle Time Minutes/wafer Propagation Loss 0.11 dB/cm (sm wg) Polarization Effects Birefringence = 10-6 PMD = 0.01 ps (1 cm sm wg) PDL = 0.01 dB (1 cm sm wg) Dynamic Provisioning dn/dT = -3.2x10-4 Compactness, Density ∆n = 0-30% Reliability Proven Function Availability Static & Dynamic in Polymer Active by Hybrid Integration

Propagation Loss = 0.11 dB/cm Pigtail Loss = 0.14 dB per side

Chip Length [mm] 10 20 30 Insertion Loss [dB] 0.0 0.2 0.4 0.6 0.8 1.0

dn/dT = -3.2x10-4

Temperature [ C] 20 30 40 50 60 Refractive Index (n) 1.345 1.350 1.355

°

DuPont Polymer Photonic IC’s

Key Properties at 1550 nm

WDL < 0.05 dB

Wavelength (nm) 1500 1520 1540 1560 1580 Insertion Loss (dB) 0.0 0.2 0.4 0.6 0.8 1.0

Low I nsertion Loss Low Pow er Consum ption Low W avelength Dependence

28

Polymer 1x2 Digital Optical Switches

Transfer Curve

Heater Power (mW) 10 20 30 40 Optical Output (dB) 40

• 30
• 20
• 10
• 'ON' Arm Output

'OFF' Arm Output

Digital Range

Heater Electrode (ON) Heater Electrode (OFF) Bonding Pad Channel Waveguide Optical Signal IN Optical Signal OUT

~0.1°

29

Attenuation: 30 dB Sensitivity: 20 dB/mW

• Max. Power Consumption: 1.5 mW

Response Time: 3 ms

Low Power Polymer MZI VOA

Heater Power (mW) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Optical Output (dB) 30

• 20
• 10

30

Polymer-Based 8x8 Intelligent OXC

I ntelligent OXC

8 x8 Sw itch (112 1x2 Switches) + 8 Taps + 8 VOAs

Variable Optical Attenuator Optical Pow er Tap 1 x2 Digital Optical Sw itch

• Strictly non-blocking OXC
• Power monitoring
• Channel balancing

Perform ance Characteristics

• Insertion Loss (fiber to fiber): 5 dB
• PDL @ 0 / 15 dB Atten: 0.1 / 0.3 dB
• WDL (1528 – 1610 nm): 0.1 dB
• TDL (-5 – 70°C): 0.1 dB
• ODL (-30 – +20 dBm): 0.1 dB
• Extinction: 45 dB
• Crosstalk (any port to any port): 50 dB
• Return Loss: 50 dB
• Power Consumption: 2.5 W
• Response Time: 3 ms
• CD: 0.1 ps/nm, PMD: 0.01 ps

Simple control of switching elements from common drive voltage

Total Footprint with PCB: 10 in2

31

Telcordia Qualification

Passed GR-1 2 0 9 -CORE/ GR-1 2 2 1 -CORE

PASS Cable Retention (3.4 lb load, 1 minute) PASS Lifetest (70°C, 2000 hours, in-situ operation & test) PASS Fiber Side Pull (0.5 lb load, 90° angle) PASS High Temperature Storage (85°C, 2000 hours) PASS Mechanical Shock (500 G, 6 directions, 5 times/direction) PASS Vibration (20-2000 Hz, 3 axes, 4 cycles/axis) PASS Thermal Shock (0°C to 100°C, 15 cycles) PASS Temperature Cycling (-40°C to 85°C, 100 cycles) PASS Temperature-Humidity Aging (85°C/85%RH, 336 hours)

Test Result Telcordia Tests GR-1209-CORE/GR-1221-CORE

32

Telcordia Qualification Results

1 2 3 4 5 6 7 8 9 10

• 0.5
• 0.4
• 0.3
• 0.2
• 0.1

0.0 0.1 0.2 0.3 0.4 0.5

Change in I nsertion Loss ( dB) Num ber of Channels

1528 nm 1550 nm 1565 nm

Passed Telcordia qualification w ith large m argin Narrow data distribution around 0 dB IL change Changes are on order of measurement error

33

Reliability of Polymers and Devices

Highly Accelerated Stress Tests ( HAST)

Lifetime > 20 years at maximum

• perating temperature of 150°C
• 0.5
• 0.4
• 0.3
• 0.2
• 0.1

0.1 0.2 0.3 0.4 0.5 1000 2000 3000 4000 5000 6000 Duration (hours) Transmission Variation (dB/cm)

20-year degradation <0.08dB/cm at 17 dBm input power <0.02dB/cm at 10 dBm input power

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Time (hours)

• 0.5
• 0.4
• 0.3
• 0.2
• 0.1

0.0 0.1 0.2 0.3 0.4 0.5

Insertion Loss Variation (dB)

5000 Hours, 175°C

Device 1 Device 2 Device 3 Device 4

175°C, 5000 hours

10-cm-long waveguides (1550 nm)

32 dBm (1.5 W), 6000 hours

(1550 nm)

Stability with High Temperature Stability with High Optical Power

Polymer lifetime well over lifetime of other components in system

Optical intensity in polymer waveguide = 2.5x1010 W/m2 → 1 0 0 x optical intensity

• n the surface of the Sun

34

Thank You

louay.eldada@usa.dupont.com http://www.photonics.dupont.com