Silicon Optical Modulators(硅基光調制器)

SiliconOpticalModulatorsRecentdevelopmentsinfabricationofHighSpeedModulatorsJee290fOutlineMotivationPng,Reed,etal.workfromSurrey.ShowsbasicprincipleandgivesoneofthetwomajordesigntypesInteldeviceHistorymakingdevice,designedandfabricatedinalternatemajordesigntype.ConclusionsMotivationVeryclear:SimodulatorsmeansCMOSintegrationandusingallourexperienceinsiliconmicromachining.Unfortunately,priorto2003thefastestSiopticalmodulatorwas~20MHz(LithiumNiobatemodulatorsare~10GHz).p-i-nSiOpticalModulators1/4FollowstheworkpresentedbyPng,Reed,etalfromSurreyUniversity(UK).p-i-nSiOpticalModulators2/4VDisappliedtoAnodevs.Cathode.→forwardbiasedp-i-njunction.→eandholesinjectedintoguidingregion→changesrefractiveindexp-i-nSiOpticalModulators3/4n=ne+nh=-[8.8x10-22(Ne)+8.5x10-18(Nh)0.8]=e+h=8.5x10-18(Ne)+6.0x10-18(Nh)FromR.A.Soref&B.R.Bennett“ElectroopticalEffectsinSilicon”Jour.OfQuan.Elec.1987.p-i-nSiOpticalModulators4/4Simulationresultsshowmodulationcanbeoptimizedto1.3GHzanda180at.7mAofcurrent.However,performanceisverydependantondopingprofileandacriticaldimensionsarenotverytolerant.Asoflate2003,fabricationisunderway.MOSSiOpticalModulators1/4Stillusestheplasmadispersioneffect,butimplementsaMOScapacitortoinducechangeinfreecarrierdensityinsteadofa p-i-ndevice.Againdesignedforsinglemode1.55m.MOSSiOpticalModulators2/4

ApplyVDtopoly.Chargeaccumulationonbothsidesofgateoxide.Ne=Nh=[/etoxt]*(VD–VFB)ne=-8.8x10-22Nenh=-8.5x10-18(Nh)0.8=(2/)neffLMOSSiOpticalModulators3/4ImplementedphaseshifterinbotharmsofaMZI.ForVD=7.7V→16dBtotalswitch.Lossisthebigkey:~15.3dBinsertionloss(~4.3dBfromcoupling&~6.7dBfrompolyguides).MOSSiOpticalModulators4/4See3dBrolloffat>1GHzfromMOScap.Switchingtestonpsuedo-randomtimesignal.ConclusionMOSmodulatorhaspoorlossfiguresandstillanorderofmagnitudeslowerthancommercialmodulators.IntelarguesthesecanbothbetheoreticallyfixedbydecreasingthesizeofthedeviceandusingSiintheguideregioninsteadofpoly(stillintegrable?).P-i-nmodulatorisstillbeingfabr