信息获取技术和材料PPT

光电探测器按光电转换方式，光电探测器可分为:光电导型、光生伏打型（势垒型）和热电偶型。光电转换中根据探测的光子波长分为:狭能隙半导体材料（红外）和宽能隙半导体材料（可见和紫外）。宽能隙材料以Si、Ge、和GaN、AlN等为主，狭能隙半导体材料主要为铅盐、碲镉汞、SbIn等。近期光电探测器最大的进展在两个方面：(1)用超晶格（量子阱）结构提高了量子效率、相应时间和集成度；（2）制成了探测器阵，可以用作成像探测。两者结合后最典型的例子为可以制成探测灵敏度极高的HgCdTe红外焦平面列阵（FPA），并成功地应用于红外遥感、成像等。Photodetector:convertlightintoelectricitythroughthephotoelctriceffectRequirements:highsensitivity,fastresponse,lownoise,lowcost,andhighreliabilityinpRPIRistheresponsivityofthephotodetector(A/W)RqhvhvPqIrateincidencephotonrategenerationelectroninp)exp(1WpPinabsthebandwidthofaphotodetectorisdeterminedbythespeedwithwhichitrespondstovariationsintheincidentopticalpower.TherisetimeTrisdefinedasthetimeoverwhichthecurrentbuildsupfrom10%to90%ofitsfinalvaluewhentheincidentopticalpowerischangedabruptly.RCtrrT9lntristhetransittimeandRCisthetimeconstantoftheequivalentRCcircuit.ThetransittimeisaddedtoRCbecauseittakessometimebeforethecarriersarecollectedaftertheirgenerationthroughabsorptionofphotons.Themaximumcollectedtimeisjustequaltothetimeanelectrontakestotraversetheabsorptionregion.Thereisatrade-offbetweenthebandwidthandtheresponsivity(speedversussensitivity)ofphotodetector.Often,theRCtimeconstantRClimitsthebandwidthbecauseofelectricalparasitics.Thesehigh-speedphotodetectorsshowflatresponseinbothamplitudeandphaseupto25GHzandareoptimizedforfrequency-domainapplications.Thehigh-sensitivityModel1414near-IRphotodetectorsuse25-µm-diameterback-illuminatedInGaAsSchottkyphotodiodeswithpeakresponsivitiesof0.6A/Wat1300nm.Theactivelayeristwiceasthickasinourultrahigh-speedModel101Xmodule,producinga50%greaterresponsivitybetween950nmand1650nm.Theconversiongainwitha50-Wloadis15V/W.25-GHzNear-IRPhotodetectorU2tXPDV2020R-VF-FPphotodetectorUltra-highspeedopticalpulsewaveformmeasurementisAchievedbyusingthesub-picosecondopticalpulsegenerationtechnologywithapassivelymode-lockedfiberlaserandthenonlinearopticaltechnologywiththesum-frequency(SF)lightgeneration.