WDM board-level optical communications

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1 MIT Microphotonics Center Spring Meeting, May 22 nd WDM board-level optical communications Jürgen Schrage Siemens AG,, Germany

2 Outline Introduction to board-level optical communications, WDM motivation WDM technology evaluation project Summary / Estimation Page Dr. Jürgen Schrage

3 Introduction

Ever increasing data rates at backplane and board-level interconnects Copper faces serious problems if data rate is scaling: - signal integrity - EMI - pin count - routing

4 Ever increasing data rates at backplane and board-level interconnects Copper faces serious problems if data rate is scaling: - signal integrity - EMI - pin count - routing complexity - more layers - power consumption => Bandwidth density will not scale! Similar data rate requirements for PCIe, QPI, HT, Infiniband Page Dr. Jürgen Schrage

Approach: board-level optical communications (basic principle: embedded waveguides in board and backplane) Electrical Input Driver Laser Diode Optical Interface Optical Waveguide

5 Approach: board-level optical communications (basic principle: embedded waveguides in board and backplane) Electrical Input Driver Laser Diode Optical Interface Optical Waveguide Optical Interface Photo Diode TIA Electrical Output α 1 α 2 n cladding n core embedded waveguides micro-optical interface Tx, LD Rx, PD optical waveguide Page Dr. Jürgen Schrage

6 Key building blocks, eco system (the way to board-level optical communications) Technology Infrastructure board-level waveguide technology device packages with e/ o conversion (incl. WDM*) and optical i/o s corresponding computer / system architectures mass-production and assembly techniques and facilities Board-level optical communication ready for commercial deployment optical coupling technology, board-to-x connectors etc. simulation and design tools technology standards skilled personnel, enabled suppliers, multiple sources * If applicable Page Dr. Jürgen Schrage

7 Key building blocks, eco system (the way to board-level optical communications) Technology Infrastructure board-level waveguide technology device packages with e/ o conversion (incl. WDM*) and optical i/o s corresponding computer / system architectures mass-production and assembly techniques and facilities Board-level optical communication ready for commercial deployment optical coupling technology, board-to-x connectors etc. simulation and design tools technology standards various implementation concepts skilled personnel, enabled suppliers, multiple sources * If applicable Page Dr. Jürgen Schrage

8 Implementation concepts (extract*) * from Tech Brief Presentation on Board-level Optical Communication Timeline and Technology Barrier Analysis, October 21 st, 2008 Present Mainstream Variant: MM, polymere channel waveguides, 850 nm VCSELs, hybrid integrated package, coupling with passive alignment, 10 Gbps per waveguide, single wavelength, up to 1 m (backplane), several tens of waveguides per bus Gbps per bus. Foreseeable: => Data rates of copper will be in the same region (20 Gbps up to 1 m) in the short term, limited potential of increasing the VCSEL data rates: Gbps, present mainstream variant provides moderate potential of scalability of bandwidth density. => WDM motivation. Long Term Variant Application of WDM? 1310, 1550 nm, integrated photonics, coupling/alignment? several Gbps per waveguide, SM waveguides. Page Dr. Jürgen Schrage

9 Estimation of timeline (extract*) * from Tech Brief Presentation on Board-level Optical Communication Timeline and Technology Barrier Analysis, October 21 st, 2008 Possible timeline scenario for implementation variants of board-level optical communication. Long Term Variant integrated photonics 1310/1550, SM, WDM Scenario Present Mainstream Variant VCSEL, 850nm, polymere, MM, single wavelength Copper 2008 near 2010 mid term 2015 long term 2020 more interconnects with smaller distances added (backplane down to MCM) Page Dr. Jürgen Schrage

10 WDM technology evaluation project (started in April 2009)

11 Project contributors Innolume GmbH, Dortmund, Germany (project leaderschip) University of Dortmund, Germany University of Paderborn, Germany Fraunhofer IZM, Berlin, Germany Fujitsu Technology Solutions GmbH / TEC, Paderborn, Germany Siemens AG / C-LAB OIT, Paderborn, Germany Page Dr. Jürgen Schrage

12 Overall objective Demonstration of a 100+ Gbps WDM optical link based on an optical source and a single Photonic Integrated Circuit via: a) fiber and b) board-level waveguide (PoC) PIC Modulators PIC Detectors Optical source DEMUX MUX DEMUX Digital Inputs Digital Outputs Page Dr. Jürgen Schrage

13 Objective: Optical Source Comb laser as light engine => single low-cost light source, instead of a multiple wavelength laser array PIC Modulators PIC Detectors Comb laser DEMUX MUX DEMUX Digital Inputs Digital Outputs Page Dr. Jürgen Schrage

Laser pumps more than 200 channels with power above 1 mw per

14 Comb laser (currently prototype for 1200nm regime) Conventional laser technology Innolume s technology Single Laser pumps more than 200 channels with power above 1 mw per channel (lab demonstration) Laser emission Page Dr. Jürgen Schrage

15 Comb laser Target parameters for the comb laser in the project Central wavelength: 1310nm Number of modes: >10 Mode spacing: 0.8nm Power of each mode: >1 mw RIN of each mode: <0.3% Page Dr. Jürgen Schrage

16 Objective: Photonic Integrated Circuit (PIC) Development of a single PIC with MUX, DEMUX, modulator, detector functionality PIC Modulators/ Detectors PIC Modulators/ Detectors Comb laser DEMUX MUX DEMUX Digital Inputs Digital Outputs Page Dr. Jürgen Schrage

17 GaAs PIC Concept: MUX, DEMUX by Arrayed Waveguide Grating (AWG) Electroabsorption Modulator (EAM) based on diluted nitride Input MUX DEMUX Output Page Dr. Jürgen Schrage

18 Objective: Board-level waveguides Investigation of board-level optical waveguide technologies towards 1310nm and use of SM for board-level interconnects. GaAs PIC Modulators/ Detectors GaAs PIC Modulators/ Detectors Comb laser DEMUX MUX DEMUX Digital Inputs Digital Outputs Page Dr. Jürgen Schrage

19 One approach: waveguides in a thin glass foil Realisation of waveguides by a double sided ion exchange process waveguides Page Dr. Jürgen Schrage

20 Board-level waveguides based on thin glass foils Waveguides show grade index profile Page Dr. Jürgen Schrage

material results in an optical layer (cross section) Thin glass foil

21 Board-level waveguides based on thin glass foils Realisation of an optical layer for board-level interconnects Lamination of foil into PCB material results in an optical layer (cross section) Thin glass foil with waveguides and alignment marks (top view) Page Dr. Jürgen Schrage

Board-level waveguides based on thin glass foils Sample with multimode waveguides parameters Thickness of foil: 300 µm Number of waveguides: 24 Waveguide length: 10 cm

22 Board-level waveguides based on thin glass foils Sample with multimode waveguides parameters Thickness of foil: 300 µm Number of waveguides: 24 Waveguide length: 10 cm Routing: parallel, straight Vertical pitch: 250 µm Horizontal pitch: 250 µm Data rate / waveguide: 10 Gbps (demonstrated at FhG lab) Page Dr. Jürgen Schrage

$Characteristics at 1310 nm (refractive index, diffusion depth) Page 23 2009-05 Dr.$

23 Board-level waveguides based on thin glass foils Characterization multimode waveguides Characteristics at 1310 nm (refractive index, diffusion depth) Page Dr. Jürgen Schrage

$results Characteristics at 1310 nm (refractive index, diffusion depth) Page 24 2009-05 Dr.$

24 Board-level waveguides based on thin glass foils Characterization singlemode waveguides, first results Characteristics at 1310 nm (refractive index, diffusion depth) Page Dr. Jürgen Schrage

25 Summary / Estimation

26 Summary / Estimation (from today s point of view) Beside single wavelength, WDM will arise in the long term to meet ever increasing bandwidth requirements inside the box. Integrated photonics (e.g. QD/comb laser, PIC) will be used for WDM Tx and Rx devices. Resulting wavelength regimes (1300nm, 1500nm) require suitable board-level waveguide materials (low loss). Also at board-level a single mode waveguide technology has to be expected. Challenge: the smaller dimensions of single mode will require the development of smart packaging and coupling technologies, in particular for the device-to-board interface (optical pin - to - embedded SM waveguide) => cost! Multimode polymer waveguide technology + VCSEL, suitable for 850nm, will continue. Some evaluation work towards WDM board-level optical communications has just started. Page Dr. Jürgen Schrage

27 Acknowledgement Thanks to Guido Vogel, Igor Krestnikov, Greg Wojcik, Manfred Bayer, Dmitri Yakovlev, Henning Schröder, Rolf Schuhmann, Oliver Stübbe, Bernhard Homölle. The R&D work mentioned in this presentation is partly funded by the Ministry of Research of the NRW state, Düsseldorf, Germany. Page Dr. Jürgen Schrage

28 Thank you!

29 Contact Siemens AG, Optical Interconnection Technology Dr. Jürgen Schrage Fürstenallee 11 D Paderborn Germany Phone: Page Dr. Jürgen Schrage

30 Backup

31 About the thin glass approach Page Dr. Jürgen Schrage

Zukunftstechnologie Dünnglasbasierte elektrooptische. Research Center of Microperipheric Technologies

Zukunftstechnologie Dünnglasbasierte elektrooptische Baugruppenträger Dr. Henning Schröder Fraunhofer IZM, Berlin, Germany Today/Overview Motivation: external roadmaps High Bandwidth and Channel Density