飞秒激光在BBO晶体中倍频效率的数值计算

BBO＊吕铁铮1)　王　韬2)　钱列加2)　鲁　欣1)　魏志义1)　张　杰1)1)(,　100080)2)(,　200433)(2001515;20011113)　　BBO,,.,100fs2mm、ⅠBBO,.:,PACC:4260,4255B,4250＊(:19825110,69878032)863-410.1.引言,.5fs[1],Cr:forsterite[2],Cr:YAG[3].,、,.,,,.,,,,;,,.2mmBBO(b-bari-umborate,),60%[4].,,,,,,、.[5],,[6].BBO,(splitedFouriermethod),,.,100fs2mm、ⅠBBO,.2.飞秒脉冲激光倍频的原理及过程分析　　,,,,,,.:k(2ω)=2k(ω),(1)dkdωω=dkdω2ω,(2)ω,k,ki=niωc.516200261000-3290200251(06)1268-04　　　ACTAPHYSICASINICAVol.51,No.6,June,2002c2002Chin.Phys.Soc.,:,Ⅰ,Ⅱ.BBO,,Ⅰ,0+0※e,no(ω)=ne(2ω,θ).(3)　　no,ne,Sellmeier,n2e=2.3753+0.01224(λ2-0.01667)-0.01516λ2,n2o=2.7359+0.01878(λ2-0.01822)-0.01354λ2.(4)μm.ne(θ)=nonen2osin2θ+n2ecos2θ,sin2θm=n2e(2ω)[n2o(2ω)-n2o(ω)]n2o(ω)[n2o(2ω)-n2e(ω)].(5)　　deffI(θ,)=(d11cos3-d22cos3)cosθ+d31sinθ.(6),d11=1.6×10-12mV,d22,d31,BBOdeffI(θ,).,,,,.,,,Δu-1=u-1ω-u-12ω=β1(ω)-β2(ω).(7)　　Δu,Lgvm=τpΔu,,τp.,100fs,BBOΔu=200fsmm,Lgvm=0.5mm.,,,zLgvm.,,.,d2dω2=(2Ldndω+ωLd2ndω2)c,d3dω3=(3Ld2ndω2+ωLd3ndω3)c,(8)c,d2dω2(GVD),BBO.,,,,.BBO800mm,Ldis(ω)Lcry,Ldis(2ω)Lcry,.3.数值求解方法:,,At,;,,、.,,.,,,Δk,A1z=iK1A2A＊1exp(-iΔkz),(9)A2z+1ΔuA2t=iK2A1A＊1exp(iΔkz),(10)Ai(z,t)(i=1,2,),zBBO.,,,,,:Az=(D(+N()A,(11)D(,,N(,,,,,,A(z+h,T)≈exp(hD()exp(hN()A(z,T).(12)exp(hD(),D(,N(,Baker-Hausdorf,　　12696:BBO(12h)[D(,N(],h.1　,1.,(100fs,800nm,1.7W).2BBO,,,,,.:,,2mmBBO,;,Δk,,;,η=60%,,Δk.3100fs.,.,2mm,,,,,,2　100fsBBO3　100fsBBO,.:,,.Lcry～gvm,,,,.2mm.4.结论,,,,.,,.1270　　　　　　51[1]EllR,MorgnerU,KrtnerFX,FujimotoJG,IppenEP,ScheuerV,AngelowG,TschudiT,LedererMJ,BoikoAandLuther-DaviesB2001Opt.Lett.26373[2]SeasA,PetricevicVandAlfanoRR1993Opt.Lett.18891[3]SennarogluA,PollockCRandNathelH1994Opt.Lett.19390[4]XiaJF,WeiZYandZhangJ2000Optics&LaserTechnology32241[5]YaoJQ1995NonlinearOpticalFrequencyConversionandTunableLasers(Beijing:SciencePress)[1995(:)][6]YaoJQ,LiuHandAshokP1995ActaOpt.Sin.6641[7]YanovskyVPandWiseFW1994Opt.Lett.231952[8]AndreoniA,BondaniMandPotenzaMarcoAC1998Opt.Com-mun.154376CalculationoffrequencydoublingefficiencyoffemtosecondpulsesinBBOcrystals＊LǜTie-Zheng1)　WangTao2)　QianLie-jia2)　LuXin1)　WeiZhi-Yi1)　ZhangJie1)1)(LaboratoryofOpticalPhysics,InstituteofPhysics,ChineseAcademyofSciences,Beijing　100080,China)2)(StateKeyLabforAdvancedPhotonicMaterialsandDevices,FudanUniversity,Shanghai　200433,China)(Received15May2001;revisedmanuscriptreceived13November2001)AbstractThispaperpresentsacalculationoffrequency-doublingefficiencyoffemtosecondpulsesinBBOcrystalsusingSplitedFouri-erMethod.Thismethodcanclearlyprovidephysicalpictureoffrequency-doublingprocessoffemtosecondpulses,whilekeepingcalculationsimple.Thecalculatedconversionefficiencyfora2mmlongBBOcrystalagreeswellwithexperimentalmeasurements.Keywords:femtosecondlaser,doubled-frequencyPACC:4260,4255B,4250＊ProjectsupportedbytheNationalNaturalScienceFoundationofChina(GrantNos.19825110,69878032).12716:BBO