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
Use of ROADM in Optical Networks Long Haul Metro ROADM Used for Connectivity (1x4, 1x8) Core ROADM Used for Add/Drop Access Access Access (1x5, 1x9, 1x11) Optical Switch (OXC) LONG HAUL ACCESS METRO OXC Distribution ROADM Feeder Ring Network Backbone Network Network DEMUX FTTP SPLI TTER Consumer 2
Migration Toward Agile Optical Networks Optoelectronic functions needed in agile optical networks: • Tunable Lasers • ROADMs Netw ork New Justification Com patibility Function Com ponents Fixed functions Fixed DW DM lasers, Fixed OADM Narrow tunable laser I nventory reduction Drop-in for fixed laser Therm al-tuned DFB Full-band tunable laser I nventory system Drop-in for fixed transponder External-cavity laser sim plification λ blocker + fixed filters Type I ROADM Stranded capacity Dual-use as DGE reduction, sim ple or Dem ux/ Sw itch/ Mux Lim ited flexibility engineering rules PLC Type I I ROADM No m anual intervention, Retain blocker, add tunable laser, no Tunable filters/ lasers Any λ to any port m onitor & control im pact to thru path; or all PLC solution, or OXC can be m ore cost-effective; or W SS or W SS Degree 2 Higher-Degree ROADM Ring-interconnect w / o Select locations only; interop w ith other W SS Any com bination of λ ’s OEO nodes, sam e lasers to any port Optical Sw itch Mesh protection, etc. Select locations only Large W SS ( aka OXC) RHK (partial) Autonom ous Agility Optim um utilization Sam e physical layer hardw are I ntegrated m anagem ent Minim um OpEx 3
ROADM Use in Networks Market Com ponent System Carriers (Technology) (System Suppliers) Vendors Vendors Avanex, JDSU, DuPont, Lucent, Ciena, Qwest (Lucent), Verizon Long-Haul LightConnect Marconi, Siemens (Lucent), GigBE project (Ciena), (Wavelength Blocker) MCI (Ciena), BT (Marconi), MCI (Siemens), AT&T (Siemens), Broadwing (Corvis) Avanex, JDSU, DuPont, Alcatel/Tropic, Lucent Verizon, MCI, SBC Metro LightConnect, CoAdna, (Alcatel/Tropic), BellSouth (Wavelength Blocker) Polycromix, Xtellus (Tellabs), NTT JDSU, DuPont, OpTun, Cisco, Tellabs, Hitachi Metro Comcast, Cox , Brighthouse Chromux, Neophotonics, (Demux/Switch/Mux) (Fujitsu), Shaw NEL JDSU, DuPont, CoAdna, Fujitsu, Meriton Metro RHK (partial) Engana, Metconnex, (WSS) LichtConnect, Capella 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. 4
ROADM path lags tunable laser by 2 years ROADM Laser Wide Higher degree laser (~40 ch) Integrated ROADM Demux/ Switch/Mux Moderate “Type II” (~20 ch) Wavelength Selective Switch expected “Type I” Narrow ROADM (~8 ch) laser Blocker + Fixed Fixed Source:RHK Tunable 2003 2004 2005 “over 1000 Filters/Lasers shipped” skipped? -JDSU 12/01/04 5
ROADM Types Wavelength-Blocker-Based Broadcast and Select Blocker as DGE Type II Higher-Degree ROADM Type I Blocker Blocker Blocker Blocker EDFA Blocker Combiner Combiner Splitter Splitter Splitter Combiner Tunable Tunable Tunable Tunable λ λ λ λ λ λ λ λ Lasers Filters/Rx Filters/Rx Lasers Fixed Filters Fixed Lasers Integrated Demux/Switch/Mux LC- or MEMS-Based WSS Type II or Higher-Degree ROADM Type I Type II Higher-Degree ROADM Wavelength Selective Switch Combiner Splitter Tunable Filters/Rx OXC OXC Tunable Lasers 6
Wavelength-Blocker-Based Type I ROADM W avelength Blocker Old Generation: Splitters at Drop, 1 Combiners at Add OPM Splitter Splitter 2 Dem ux M . . u . . . . x DROP ADD N … 1 xN ( or 1 xM) … … … Nx1 ( or Mx1 ) Splitter Com biner … … Tunable Filters Common Characteristics: ● Free-space (MEMS, LC) Receivers Transm itters ● For full reconfigurability: Tunable lasers at ADD New Gen: ● Splitters/Combiners New Generation: W avelength Blocker replaced with Demux/Mux Demux at Drop, ● Mux at Add 1 No tunable filters at DROP 2 3 0 % / 7 0 % Splitter 3 0 % / 7 0 % Splitter Dem ux x . OPM u . . M . . in out . M u x Dem ux N . . . Drop Channels Add Channels 7
PLC-Based Type I ROADM λ 1 λ 2 λ 1 . 5% Tap . . . . D . λ 32 . . M E . . . U . M IN OUT X U λ 32 X λ 1 λ 2 . . . Control Electronics λ 32 15%Tap OUT IN X D E M U λ 1 λ 32 λ 1 λ 32 DROP ADD Power, Data Note: Both express and “Add” channels are balanced w ith the built-in VOA array 8
Type II ROADM Configurations Full N (or M of N) Reconfigurability W B-Based Broadcast OCM Splitter Splitter and Select Dem ux M • . u Free-space, MEMS, LC . . x DROP • Higher IL ▼ ADD • … Difficult to upgrade ▼ … … 1 xN ( or 1 xM) … Nx1 ( or Mx1 ) Splitter Com biner • W avelength Blocker Reliability issues ▼ … … Tunable Filters Tunable • Tunable filters at DROP ▼ Transm itters Receivers • For full reconfigurability: Tunable lasers at ADD ▼ PLC-Based Dem ux/ Sw itch/ Mux • Large component count ▼ • Expensive ▼ DCE OCM 2 x 1 DCE OCM 1 x 2 Dem ux . . . . . . . . . . . . Mux . . . . . . • Can be single PLC ▲ • Lower IL ▲ • Easy to upgrade ▲ • NxM & MxN at A/D give full reconfigurability ▲ • Integration-friendly ▲ ADD DROP • Typical Today: Small component count ▲ MxN OXC NxM OXC N = 8 , 1 6 , 3 2 , 4 0 • Low cost ▲ M = 4 , 8 Receivers Transm itters 9
PLC-Based Type II ROADM λ 1 λ 2 . . . 5% Tap λ 32 . D . . . 15%Tap . M E . . . U M . IN X U OUT X E M U X D Control Electronics λ 1 λ 32 λ 1 λ 32 ADD DROP Power, Data 3 2 x8 OXC 8 x3 2 OXC Receivers Transm itters 10
Demux/Switch/Mux Type II ROADM Fully Reconfigurable East/West Separated Architecture 8 λ / Fiber 1 1 Drop any λ to any port Add any λ from any port DEMUX MUX Fiber 1 Fiber 1 I n W est Out East Polym er PLC includes 1 16 1x2 Switches 8 From W est 8 1 8 8 Drop 1 − 8 Add 1 − 8 16 VOA’s 8 x8 OXC 8 x8 OXC To East 16 Taps 1x2 Switch 16 Photodiodes East W est Power Tap 2 8x8 Switches Photodiode To W est From East Add 1 − 8 Drop 1 − 8 Chip 66 Functions Chip VOA Each 8x8 Switch is 8 x8 OXC 8 x8 OXC 112 1x2 Switches 1 8 1 8 1 1 → 2 8 8 Elementary Functions DEMUX MUX Fiber 2 Fiber 2 Out W est I n East 8 8 11
Fully Reconfigurable PLC-Based 8-Channel Demux/Switch/Mux Type II ROADM Out ( W est) I n ( East) Out ( East) I n ( W est) Sw itch/ VOA Optional Tap/ PD 1 2 7 0 / 3 0 coupler x u M x u D M 8 D M u x 8 x8 Sw itch Control Electronics 8 x8 Sw itch 2 8 1 ADD ( W est) DROP ( East) Note: Mux and Dem ux are based on thin film filters 12
Node Cascading Simulation Layout Cascade of 16 ROADM nodes (32 AWG’s) Simulation tools and 1 6 iterations 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 of ROADM passband due to temperature variation and center frequency inaccuracy of AWG filters is used 13
Bandwidth of Cascading AWG Filters Concatenation of Flat-Top AWG Filters 90 3-dB BW (GHz) 80 0.5-dB BW(GHz) 70 Power (3-dB BW (GHz)) Power (0.5-dB BW(GHz)) 60 Bandwidth (GHz) 50 y = 79.131x -0.252 40 30 20 y = 50.271x -0.2521 10 0 0 5 10 15 20 25 30 35 Number of Flat-Top AWG Filters 14
Simulation Conditions (16 Nodes) Laser center Dem ux filter 3 -dB Mux filter 3 -dB ROADM Total frequency( THz) center ( THz) center ( THz) Loss ( dB) Run1 194.0000 194.0000 194.0000 10.0 Run2 194.0111 194.0000 194.0000 10.0 Run3 194.0111 194.0050 193.9950 10.0 Run4 194.0111 194.0050 193.9950 20.0 Run 1 Run 2 Run 3 Run 4 15
Cascading Simulation Conclusions 2.10E+01 • DuPont PLC ROADM meets 2.05E+01 bandwidth requirements for 16-node 2.00E+01 DWDM rings 1.95E+01 Q Value 1.90E+01 – Bandwidth at 0.5dB is over 40 GHz 1.85E+01 for each ROADM 1.80E+01 1.75E+01 – Bandwidth at 0.5dB is over 20 GHz 1.70E+01 after 16 cascading nodes (32 AWG’s) 193.980 193.990 194.000 194.010 194.020 Laser Center Frequency (THz) • DuPont PLC ROADM allows use of 1.00E-13 low cost, low accuracy lasers for 16- 1.00E-15 node rings 1.00E-17 – Bit error rate (BER) lower than 10 -17 BER 1.00E-19 – Lasers with +/-10 shift of center 1.00E-21 frequency can be used without any 1.00E-23 system performance degradation 1.00E-25 after 16 cascading nodes 193.980 193.990 194.000 194.010 194.020 Laser Center Frequency (THz) 16
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