Next Gen ROADMs “Less” is more: Colorless, Directionless, Contentionless, Gridless Krishna Bala, Ph.D Exec VP WSS Group bala@oclaro.com ECOC 2010 Turin Italy

Next- Gen ROADM requirements Architectural Choices Outline Next- Gen ROADM requirements Architectural Choices Implications for WSS devices

Generations of ROADMs 1st Gen ROADMs introduced the following features: Re-configurability in add/drop channels However, these nodes were restricted to 2 directions 2nd Gen ROADMs introduced the following features: Multi-degree capability (e.g. 4 or 8 directions per node) However, these nodes are “colored” and “directional” 3rd Gen ROADMs will introduce more “Mesh” features: Significant flexibility in provisioning and restoration Colorless, Directionless, Contentionless and “Gridless” (Flexible Spectrum actually)

2nd Gen ROADM: 8 degree example Colored and Directional 8x1 WSS Degree 2 Passive splitter 8x1 WSS Degree 1 Degree 8 8x1 WSS Add/Drop AWG AWG AWG AWG AWG AWG Tx Rx Colored: Each “chassis slot” is associated with specific “laser color” Directional: Each laser is associated with a specific direction 4

Requirements for 3rd Gen ROADMs New Features for Mesh ROADMs/WSS North In North Out West In East In ROADM Node West Out East Out Local Drop ports Local Add ports Colorless add/drop – No blocking in wavelength assignment on any Add/Drop Contentionless add/drop – No blocking inside ROADM due to wavelength collision Directionless add/drop – Full flexibility in routing to any direction Gridless - Dynamically allocate spectrum to each wavelength 5

Requirements for 3rd Gen ROADMs New Features for Mesh ROADMs/WSS North In North Out West In East In ROADM Node West Out East Out Local Drop ports Local Add ports Of course, customers want ……. Costless  Colorless add/drop – No blocking in wavelength assignment on any Add/Drop Contentionless add/drop – No blocking inside ROADM due to wavelength collision Directionless add/drop – Full flexibility in routing to any direction Gridless - Dynamically allocate spectrum to each wavelength As a supplier, we think ………….. Priceless  6

3rd Gen ROADM: 8 degree example Adding Colorless Feature: Replace AWGs 8x1 WSS Degree 2 Passive splitter 8x1 WSS Degree 1 Degree 8 8x1 WSS Add/Drop AWG AWG AWG AWG AWG AWG Tx Rx Colored: Each “chassis slot” is associated with specific “laser color” Directional: Each laser is associated with a specific direction 7

Colorless 3rd Gen ROADM: 8 degree example 8x1 WSS Degree 2 Passive splitter 8x1 WSS Degree 1 Degree 8 8x1 WSS Add/Drop 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS 1x24 WSS AWG Tx Rx Colorless: Each “chassis slot” can associate with any “laser color” Directional: Each laser is associated with a specific direction Colorless: Requires “Scalability” in WSS port count – Large port count 8

Colorless AND Directionless 3rd Gen ROADM: 8 degree example Colorless AND Directionless 8x1 WSS Degree 2 Passive splitter 8x1 WSS Degree 1 Degree 8 8x1 WSS Passive splitter Add/Drop 8x1 WSS 8x1 WSS 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS Tx 9

3rd Gen ROADM: 8 degree example Colorless and Directionless: But, has Contention 8x1 WSS Degree 2 Passive splitter 8x1 WSS Degree 1 Degree 8 8x1 WSS Add/Drop Contention 8x1 WSS 8x1 WSS 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS Tx Rx Rx 10

MxN WXC MxN WXC 24x8 or 48x8 or …. 8x24 or 8x48 or …. 3rd Gen ROADM: 8 degree example Colorless, Directionless, Contentionless 8x1 WSS Degree 2 Passive splitter 8x1 WSS Degree 1 Degree 8 8x1 WSS MxN WXC 24x8 or 48x8 or …. MxN WXC 8x24 or 8x48 or …. 8x1 WSS 8x1 WSS 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS Tx Rx Rx Contentionless: Requires “Scalability” in WSS ports – Large port counts 11

MxN WXC 8x8 MxN WXC 8x8 3rd Gen ROADM: 8 degree example Colorless, Directionless, Contentionless with “Grouping” 8x1 WSS Degree 2 Passive splitter 8x1 WSS Degree 1 Degree 8 8x1 WSS MxN WXC 8x8 MxN WXC 8x8 8x1 WSS 8x1 WSS 8x1 WSS 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS 1x24 WSS AWG 1x24 WSS AWG 1x24 WSS Tx Rx Rx 12

Example: Add BW in 25GHz steps 3rd Gen ROADM: Colorless, Directionless, Contentionless and “Gridless” Example: Add BW in 25GHz steps -200 -175 -150 -125 -100 -75 -50 -25 25 50 75 100 125 150 175 200 Dynamic/Flexible Spectrum Addition Add BW in 25 Ghz steps Allows future-proofing for higher speed transport E.g. 400 Gb/s and 1 Tb/s Gridless: Requires Spectrum “Flexibility” in WSS Xtellus Confidential - 13 13

WSS Roadmap for 3rd Gen ROADMs WSS must be SCALABLE Large port counts 1x24 plus ports and beyond MxN where M=8 and N=24 and beyond WSS must be FLEXBILE Dynamic/Flexible Spectrum Alloction Other “Must Haves” Fast switching speed: Fast mesh restoration Green: Low power dissipation

3rd Gen ROADMs require new features Conclusion 3rd Gen ROADMs require new features Colorless, Directionless, Contentionless, Gridless 3rd Gen WSS must support Scalability in port counts Flexibility in spectral allocation Fast switching times Green low-power operation