简介:ThecrystallographicpropertiesandRamanspectraofthetitlecompoundZnCd(SCN)4,whichisanewnonlinearopticalcrystal(NLO),arereportedforthefirsttime,ThiscrystalisorthorhombicanditsspacegroupisI4^4withunitcellparametersa=1.135(0.2)nmc=0.43760(1)nm.Therearetwoformulasperunitcell.Ramanspectraofzinccadmiumthiocyanatec(ZCTC)aregivenandtheelectronactivitiesinthecrystalareshown.
简介:AnewlygrownBaGa4Se7crystalhasbeensynthesizedviatheBridgman-Stockbargertechnique.Thisnewcrystalhasadvantagesofhighnonlinearoptics(NLO)coefficients,highlaserdamagethresholds,andwidetransparentregions.TheBaGa4Se7crystalhasbrightapplicationprospectsasanonlineargainmediuminmid-infraredandterahertzregions.Inthispaper,thecrystallinestructureandsyntheticmethodoftheBaGa4Se7crystalareintroduced.Therefractiveindicesandabsorptioncoefficientsalongthreedielectricaxesbetween0.1THzand1.0THzarealsoobtained.Theterahertzdifferencefrequencygeneration(THz-DFG)characteristicsbasedontheBaGa4Se7crystalinthefrequencyrangeof0.1THzto1.0THzareanalyzedtheoreticallyandthephase-matchingconditionsarecalculated.TheapplicationofBaGa4Se7crystalsinterahertzwavegenerationisalsodiscussed.
简介:Thestabilityofthedrivecurrentisveryimportantforalaserdriver,whileitisdifficulttomaintainthecurrentstableatahighvalueforthelaserdriver.Ontheotherhand,therangeofthedrivecurrentisexpectedtobeaswideaspossibletobeappliedtodifferentkindsoflasers.Inthispaper,ahighcurrentlaserdriverforthesuperluminescentlightemittingdiode(SLED)ispresented,whichisusedintheopticfibergyroembeddedbya0.35mbipolarcomplementarymetal-oxide-semiconductortransistor(BiCMOS)process.Thelaserdriverprovidesautomaticpowercontrolandcertainvalueofcurrentdeterminedbytheexternalresister.Thesystemisbasedontheoptic-electricfeedbacktheoryandusestheclosed-loopcontroltechniquetomaintainthedrivecurrentstable.Thesystemiscapableofproducingstablecurrentrangesfrom4mAto200mAwhenthevalueofexternalresisterchanges.
简介:LinearPhaseFIRFilteronMeasuring3-DSurface①WANGYunshan,YANGFujun,LIWei(ShandongUniversityofTechnology,Jinan250061,CHN)Abstract...
简介:InthispaperthedesignandimplementationofMulti-Dimensional(MD)filter,particularly3-Dimensional(3D)filter,arepresented.Digital(discretedomain)filtersappliedtoimageandvideosignalprocessingusingthenovel3Dmultiratealgorithmsforefficientimplementationofmovingobjectextractionareengineeredwithanexample.Themultirate(decimationand/orinterpolation)signalprocessingalgorithmscanachievesignificantsavingsincomputationandmemoryusage.Theproposedalgorithmusesthemappingrelationsofz-transferfunctionsbetweennon-multirateandmultiratemathematicalexpressionsintermsoftime-varyingcoefficientinsteadoftraditionalpolyphasede-compositioncounterparts.ThemappingpropertiescanbereadilyusedtoefficientlyanalyzeandsynthesizeMDmultiratefilters.
简介:Anovelmethodfordesigningabeam-switchingantennawiththeplanedipoleispresented.Theantennaiscomposedofdoubledipolesplacedatthecenterofanactivesquarestructurethatisdividedinfourequalsectorsbymetallicsheets.Metallicpatchesattheoutsideofthestructureareusedtoenhancetheradiationperformanceoftheantenna.Ineachstep,thediodesinonesectorareon,whereasotherdiodesareoff.Thesectorwithoff-statediodesdefinesthedirectionoftheradiationpattern.AnantennamodelisdesignedonthesubstrateofFR4.Theproposedantennaoperatesfrom4.8GHzto5.5GHzwithgainof6.3dBiandF/B(fronttobackratio)of13.2dBiwhentheoperatingfrequencyis5.2GHz.Theantennaradiationpatterncanbesweptintheentireazimuthplaneinfourstepswitha3dBbeamwidthof90.Theresultsrevealthattheantennacouldbeusedinthebasestationofthewirelesscommunicationsystems.