简介：Wereportamethodforsimultaneouslyanddirectlymeasuringallsix-degrees-of-freedom(six-DOF)motionerrorsofarotaryaxis.Suchamethodcombinestheprinciplesoflaserinterferometryandlasercollimationmeasurement.Onereferencerotaryaxisandtworetro-reflectorsareusedtoachievesimultaneoussensitivitytoallsixerrorsinafull-circlemeasuringrange.Asnoseparationmodelsarerequired,ourmethodiscapableofdynamicallymeasuringtheseerrorsinrealtimeandconvenientlydeterminingtheoriginoftheerrors.Anautomaticmeasuringdeviceisbuilt.Theeffectivenessofourmethodisexperimentallydemonstrated.

简介：Weproposeanovelschemeforopticalfrequency-lockedmulti-carriergenerationbasedonadirectlymodulatedlaser(DML)andaphasemodulator(PM)incascadethroughsynchronoussinusoidalradiofrequency(RF)signal.TheoptimaloperatingzoneforthecascadedDMLandPMschemeisdeterminedviatheoreticalanalysisandnumericalsimulation.Wedemonstrate16opticalsubcarrierscanbesuccessfullygeneratedbasedonthecascadedDMLandPMschemeintheoptimalzone.Thegenerated16opticalsubcarrieshavefrequencyspacingof12.5GHzandpowerdi?erenceoflessthan3dB.Theseresultsagreewellwiththoseofthenumericalsimulation.Wealsodemonstrateintensitymodulationanddirectdetection(IM-DD)basedononeofthe16generatedopticalsubcarriers.After20-kmsingle-modefiber-28(SMF-28)transmission,thebit-errorratio(BER)of1×10-9canbeattainedforboth3.125-and12.5-Gb/sbitrates.