简介：本文采用简单方法,从现象到本质,从特殊到一般,对多普勒效应进行了系统分析,逐步推导出多普勒效应定量公式;为了易于理解,通过举例说明其应用。

简介：Inthiswork,weinvestigatethemethodstoimprovetheperformanceofthesweptsourceat1.0μmbasedonapolygonscanner,includingin-cavityparametersandboosterstructuresoutofthecavity.Thethreein-cavityparametersarethecavitylength,therotatingspeedofthepolygonscanner,andthein-cavityenergy.Withthedecreaseofcavitylength,thespectrumbandwidthbecomeswiderandthedutycyclebecomeshigher.Withtheincreaseoftherotatingspeedofthepolygon,thespectrumbandwidthbecomesnarrower,andthedutycyclebecomeslowerbuttherepetitionratebecomeshigher.Withmoreenergyin-cavity,thespectrumbandwidthbecomeswiderandthedutycyclebecomeshigher.Theboosterstructuresincludethebufferedstructure,secondaryamplifier,anddual-semiconductoropticalamplifierconfiguration,whichareusedtoincreasethesweepfrequencyto86kHz,theoutputpowerto18mW,andthetuningbandwidthto131nm,respectively.

简介：利用TCAD仿真技术,研究了电离总剂量辐射陷阱电荷对0.18μmN沟道MOSFET转移特性的影响.构建了0.18μmN沟道MOSFET的三维仿真结构,获得了在电离总剂量（totalionizingdose,TID）效应影响下,负栅压偏置时器件中电流密度的分布情况.分析了器件浅槽隔离层（shallowtrenchisolation,STI）中氧化物陷阱电荷和界面态陷阱电荷对器件泄漏电流的影响.仿真计算了N-MOSFET的转移特性,仿真结果与辐照试验结果受辐照影响的趋势基本一致,为深亚微米MOS器件的总剂量辐射效应的损伤机制提供了一种分析手段.

简介：Atheoreticaldesignispresentedfora1×Mwavelength-selectiveswitch（WSS）thatroutesanyoneofNincomingwavelengthsignalstoanyoneofMoutputports.Thisplanaron-chipdevicecomprisesofa1×Ndemultiplexer,agroupofNswitching'trees'actuatedbyelectro-opticalorthermo-opticalmeans,andanM-foldsetofN×1multiplexers.Treesutilize1×2switches.TheWSSinsertionlossisproportionalto(log2（M+N+1）)Alongwithcrosstalkfromtrees,crosstalkispresentateachcross-illuminatedwaveguideintersectionwithintheWSS,andthereareatmostN-1suchcrossingsperpath.TheselossandcrosstalkpropertieswilllikelyplaceapracticallimitofN=M=16upontheWSSsize.Byconstrainingthe1×2switchingenergyto1fJ∕bit,wefindthatresonant,narrowband1×2switchesarerequired.The1×2devicesproposedherearenanobeamMach–Zehndersandasymmetriccontra-directionalcouplerswithgratingassistance.

简介：Two-dimensional（2D）graphitecarbonnitride（g-C3N4）nanosheetshavebeensuccessfullyusedasasaturableabsorber（SA）inapassivelyQ-switchedNd:LLFlaserat1.3μmforthefirsttime,tothebestofourknowledge.Underanincidentpumppowerof9.97W,theshortestpulsedurationof275nswasacquiredwithoutputpowerof0.96Wandpulserepetitionrateof154kHz,resultinginapulseenergyof6.2μJ.Inaddition,thesaturableabsorptionbehaviorsofzero-dimensional12nmg-C3N4nanoparticles（g-C3N4-NPs）andthree-dimensionalorderedmesoporousg-C3N4（mpg-C3N4）werealsoobserved,althoughtheirmorphologyandstructurewerequitedifferentfrom2Dg-C3N4.Theexperimentalresultsintroducethepotentialapplicationofg-C3N4nanomaterialsasSAsinQ-switchedlasers.

简介：Wereportonbroadlywavelength-tunablepassivemode-lockingwithhighpoweroperatingatthe2μmwaterabsorptionbandinaTm:CYAcrystallaser.Withasimplequartzplate,stablemode-lockingwavelengthscanbetunedfrom1874to1973nm,withatunablewavelengthrangeupto~100nmandmaximumoutputpowerupto1.35W.Thebandwidthisnarrowas~6GHz,correspondingtoahighcoherence.Toourknowledge,thisisthefirstdemonstrationofwavelength-tunablemode-lockingwithwatt-levelinthe2μmwaterabsorptionband.Thehightemporalcoherentlasercanbefurtherappliedinspectroscopy,theefficientexcitationofmolecules,sensing,andquantumoptics.

简介：Byusingtheultrasound-assistedliquidphaseexfoliationmethod,Bi2Te3nanosheetsaresynthesizedanddepositedontoaquartzplatetoformakindofsaturableabsorber（SA）,inwhichnonlinearabsorptionpropertiesaround2μmareanalyzedwithahome-mademode-lockedlaser.Withtheas-preparedBi2Te3SAemployed,astablepassivelyQ-switchedall-solid-state2μmlaserissuccessfullyrealized.Q-switchedpulseswithamaximumaverageoutputpowerof2.03Waregeneratedunderanoutputcouplingof5%,correspondingtothemaximumsingle-pulseenergyof18.4μJandpeakpowerof23W.Thedeliveredshortestpulsedurationandmaximumrepetitionrateare620nsand118kHzunderanoutputcouplingof2%,respectively.ItisthefirstpresentationofsuchBi2Te3SAemployedinasolid-stateQ-switchedcrystallinelaserat2μm,tothebestofourknowledge.Incomparisonwithother2Dmaterialssuitableforpulsed2μmlasers,thesaturableabsorptionperformanceofBi2Te3SAisprovedtobepromisingingeneratinghighpowerandhigh-repetition-rate2μmlaserpulses.

简介：Wehavedemonstratedahigh-average-power,high-repetition-rateopticalterahertz（THz）sourcebasedondifferencefrequencygeneration（DFG）intheGaSecrystalbyusinganear-degenerate2μmintracavityKTPopticalparametricoscillatorasthepumpsource.Thepowerofthe2μmdual-wavelengthlaserwasupto12.33Wwithcontinuoustuningrangesof1988.0–2196.2nm/2278.4–2065.6nmfortwowaves.DifferentGaSecystallengthshavebeenexperimentallyinvestigatedfortheDFGTHzsourceinordertooptimizetheTHzoutputpower,whichwasingoodagreementwiththetheoreticalanalysis.Basedonan8mmlongGaSecrystal,theTHzwavewascontinuouslytunedfrom0.21to3THz.ThemaximumTHzaveragepowerof1.66μWwasobtainedatrepetitionrateof10kHzunder1.48THz.Thesinglepulseenergyamountedto166pJandtheconversionefficiencyfrom2μmlasertoTHzoutputwas1.68×10-6.Thesignal-to-noiseratioofthedetectedTHzvoltagewas23dB.TheacceptanceangleofDFGintheGaSecrystalwasmeasuredtobe0.16°.

简介：ZnOfilmscontainingErandGenanocrystals（nc-Ge）weresynthesizedandtheirphotoluminescence（PL）propertieswerestudied.Visibleandnear-infraredPLintensitiesarefoundtobegreatlyincreasedinnc-Ge-containingfilm.Er-related1.54μmemissionhasbeeninvestigatedunderseveralexcitationconditionsupondifferentkindsofGe,ErcodopedZnOthinfilms.1.54μmPLenhancementaccompaniedbytheappearanceofnc-Geimpliesasignificantcorrelationbetweennc-GeandPLemissionofEr3+.Theincreasedintensityof1.54μminGe:Er:ZnOfilmisconsideredtocomefromthejointeffectofthelocalpotentialdistortionaroundEr3+andthepossibleenergytransferfromnc-GetoEr3+.

简介：介绍了关于＂石墨烯纳米材料的制备、结构表征及其光致发光特性研究＂的科研型实验在近代物理实验教学中的应用,该实验关注当前科学研究的热点问题,综合运用物理、化学、材料、电子等学科有关领域的知识与技术。科研型实验激发了学生的实验兴趣,对提高学生独立思考、分析问题能力有很大的促进作用。

简介：大学物理实验是学生进入大学后受到系统的实验方法和实验技能训练的开端,学生物理实验成绩的评定方法具有重要的导学作用,惠州学院物理实验室根据学校实际情况对学生成绩的评定方法进行改革,引入新的考核指标,使得学生在掌握物理实验的基本知识、基本方法和基本技能的同时增强责任心,提高安全意识,规范实验操作行为,形成良好的行为习惯,促进学生的科学实验能力和职业素质的培养。

简介：基于地下强爆炸诱发出的具有独特性质的非线弹性摆型波的试验和理论证据,系统开展块系岩体中的非线性摆型波特性在核试验核查中的应用研究.利用自主研发的试验仪器,成功模拟出块系岩体介质中低频、低速的变形波——摆型波,并通过试验揭示了冲击扰动作用下非线性摆型波产生的力学机理与传播规律,同时还研究了由摆型波传播诱发岩块的不可逆位移、动力滑移失稳的条件.通过构造冲击扰动下岩块振动的等效振动能量表达式及变分原理,提出了摆型波传播的特征能量因子,利用特征能量因子临界阈值界定了地下爆炸不可逆位移范围.结合卫星侦察等爆炸后效应监测手段,可对地下核爆炸的当量和埋深进行有效评估,为地下大当量核爆炸试验核查提供一种新的技术手段.