Present-dayapplicationsofthehighcapacityprovidedbyopticalfibermainlyconcern point-to-pointlinks,possiblyequippedwithamplifiers.Asaconsequence,optical WDMlightpathsarestaticandareboundtobeconsideredasascarceresource.Once setup,theyremaininplace,essentiallyforever.Thus,currentopticalnetworksare staticwavelength(circuit)switched,whereopticalcross-connects(OXCs)areusedto switchtraffic[1].However,opticalcircuitswitching(OCS)perfectlyfitsforsmooth trafficofconstantbitrates,butisunsuitablefordynamicalopticalnetworkingtosup- portburstytraffic.Opticalpacketswitching(OPS)[2]hasbeenproposedforthe on-demanduseofcapacity.Althoughverypromising,thistechnologylagsbehinddue tothelackofatrueopticalrandomaccessmemory.Thisstressestheneedforon-the- flypacketprocessing,whichisimpossiblewiththecurrentstate-of-the-artall-optical logic[3].Anotherpromisingcandidateisopticalburstswitching(OBS),whichcom- binesthemeritsofpacketandcircuitswitching[4].OBShasbeenproposedtorelax thetechnologyconstraintsofOPSbyattainingthedynamic,fastsetupofvirtual lightpaths.Inanycase,itisonlytheswitchingspeedthatreallytransformstheraw bitratesintousefulbandwidth,andphotonictechnologyplaysanimportantrole towardthisaim.Tosupportdynamicopticalnetworking,opticalrouterswithfast reconfigurationcapabilityarerequired.Inrecentyearsmanyresearchactivitieshave beeninvestigatingarchitecturalsolutionsforopticalrouterimplementation[5-7].A keypointistheavailabilityoffeasibleenablingphotonictechnologytomeetarchitec- turalandoperationalrequirements. Thispaperreviewsthestateoftheartofphotonictechnologyforhigh-performance opticalswitchingandreportsrecentresearchresultsfromtheVirtualDepartmenton OpticalSwitchingandSystems(VD-S),partofthee-Photon/ONe+andICT-BONE networkofexcellence[8,9].Togetherwithanotherpapermainlyrelatedtosystem aspectsandexperimentsinphotonicswitching[10],itprovidesaquitecompleteover- viewofthecurrentresearchactivitiesinthatfieldtoofferacommonknowledgeplat- formtostimulatefurtherresearch.Thee-Photon/ONe+networkofexcellenceisan EU-fundedprojectthataimsatintegratinganddevelopingknowledgeinthefieldof opticalnetworkingandphotonictechnology.TheVD-Sworkinggroupconsistsof22 academicandindustrialpartners,anditsscopeistoidentifyanddevelopkeyswitch- ingtechnologiestomakethespectrumefficientintermsofswitchingandnotonlyin termsofcapacity.Towardthisgoal,theVD-Sworkinggroupdevelopedsynergies betweenpartnersthroughcollaborativeprojects,includingmobilityactionsforinte- gratingresearchersandforobtainingaccesstouniqueexperimentalfacilitiesand opticaltestbeds. WithinthecourseoftheVD-Sgroup,keyopticalsubsystemsthathavebeenidenti- fiedtoexhibitsignificantperformanceadvancesoverothercandidatetechnologiesare opticalbuffers,opticalmultiplexers/demultiplexers,andopticalpacket/burstswitches. However,toachievetheadvantagesofhighperformanceandlowpowerconsumption thatphotonicscanoffer,otherbuildingblockssuchaswavelengthconverters,optical logicgates,andregeneratorsmustbedeveloped.Thispaperreviewstheenabling technology,presentstherecentadvancesinthedesignanddevelopmentofsuchsub- systems,andpresentsrecenteffortstowardtheimplementationofatrueall-optical packetswitchingnode. Therestofthepaperisorganizedasfollows.Section 2 presentsenablingoptical technologiesandisparticularlyfocusedonrecentadvancesinhybridintegration, wavelengthconversion,andringresonator scapabilities.Sections 3-5 presentthe stateoftheartintheseareasandresearchresultscarriedoutandundertheorgani- zationofVD-S.FinallySection 6 concludesthepaper.