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1/9/2013JANUARY 28-31, 2013SANTA CLARA CONVENTION CENTERAdvances in Onboard Optical Interconnects:A New Generation of Miniature Optical EnginesMarc VerdiellCTO Samtec Optical GroupSamtec, Inc.01/29/2013Optical Engine? What’s That?Different things to different people In the context of this presentation (novel computer interconnects): Self contained electrical to optical transceiver unit– Miniaturized– Fits in Active Optical Cable, mounts on PCB or IC packageSeveral lanes wide (x4, x8, x12, x16 )High speed (10 Gb/s per lane and up) Intended for computer interconnects / datacom links 1
1/9/2013Anatomy of a VCSEL Based Optical EngineVCSEL Vertical Cavity Surface Emitting LaserTypically analog EO-OE link, no retiming, but reshapingTx and Rx add (programmable) pre/de emphasisVCSEL laserarrayTx InDriverRx OutTIAControlPIN photodetector arrayMicro –ControllerelectricalOptical FibersFiber transmission adds very little signal impairmentsopticalVCSELVCSEL Vertical Cavity Surface Emitting LaserAmplitude Modulated (OOK - On-Off Keying)Very small emitting areaVCSEL Array (source: Philips)Light path in optical engine (source: Samtec)Laser Emitting Area (few microns dia.)2
1/9/2013Optical Link Eyes (10 Gb/s)Optical Eye travelling in fiber(On-Off Keying)Optical Engine Received Eye(Electrical, pre-emphasis added,10m)19” Copper eye for referenceControlGenerally over I2C QSFP has hardware interrupt line for alarms“Digital Diagnostics” and settings Laser on/off per channelRx squelch per channelLoss of Rx signalTemperatureAlarms for the two aboveSome engines: transmitted and received power (additional !)Some engines: pre-emphasis and amplitude settingsLots of part informationManufacturer, part number, lot, manufacturing date, etc Max rate of cable supported Optical technology (wavelength, type of fiber ) 3
1/9/2013Single-mode and Multimode FibersSingle-mode vs. multi-mode fiber (source: Furukawa)Single-mode fiber core 10 µm, multi-mode core 50 µmFor distances below 100m, multi-mode is the standardException: Silicon Photonics based engine must use single-mode fiber and are notcompatible with standard short reach optics.Silicon PhotonicsSilicon is transparent in the long wavelength“telecom” window (1550nm)The following elements can be integrated intoa single chip Driver electronicsSingle-mode waveguidesModulatorsPhoto detectorsSilicon Photonics Chip (source: OpSIS)In practice, some are really hardReally good drive electronicsSmall modulators Any laser sources Single-mode fiber coupling Negates size advantageAlignment costHybrid Silicon Photonics Chip (source: LightWire)4
1/9/2013Continuous Technology ProgressIntegrated Photonics Silicon Photonics (e.g. Luxtera)– Good for high level of complexity / integration– Single-mode / long wavelength In Photonic integrated circuits (e.g. Infinera)– High end telecom single-mode / long wavelength / WDM/ long distanceVCSEL based technology Optical micro molding– Intel Lightpeak (consumer)– Micro-engines (Avago, Samtec) Multi-mode / short wavelength / parallel / short distanceInteroperable with standard short reachMicro-connector systems Specially adapted for miniature opticsHistorical Perspective: the SNAP1212 lane unidirectional parallel optical moduleVCSEL based, multimode fibersWas first implementation of short reach 10 Gb/s (12x 1Gb/s)Uses MPO optical connector interfaceInitially for telecom / core router applicationsLater evolved to the MEG Array connector de-facto standardMEG Array ConnectorSNAP12 Modules(Picolight/JDSU)MTP Ferrule and MPO 12fiber connector(USConnec)5
1/9/2013Small Engines – Large ModulesOptical Engines “cores” can be made very small 10x10mm footprintAvago Micropod (x12)Reflex Photonics (x12)Samtec FireFly (x12, x4 bidi)Luxte
Optical technology (wavelength, type of fiber ) 1/9/2013 4 Single-mode and Multimode Fibers . SANTA CLARA CONVENTION CENTER Advances in Onboard Optical Interconnects: A New Generation of Miniature Optical Engines Marc Verdiell CTO Samtec Optical Group Samtec, Inc. 01/29/2013 .
