光电子学与光子学的原理及应用-课后答案

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1、SolutionsforOptoelectronicsandPhotonics:PrinciplesandPracticesChapter1/2/3/71.4AntireflectioncoatingForlighttravelinginmedium1incidentonthe1-2interfaceatnormalincidence,SolutionsforOptoelectronicsandPhotonics:PrinciplesandPracticesChapter1/2/3/7r12=n1-n2==n1-n1n3n1+n1n31

2、-1+n3n1n3n1n1+n2SolutionsforOptoelectronicsandPhotonics:PrinciplesandPracticesChapter1/2/3/7Forlighttravelinginmedium2incidentonthe2-3interfaceatnormalincidence,SolutionsforOptoelectronicsandPhotonics:PrinciplesandPracticesChapter1/2/3/7r23=n2-n3=n2+n3n1n1n3-n3n1n3+n3=n

3、3n1n3-11-n3=n1+11+n3n1SolutionsforOptoelectronicsandPhotonics:PrinciplesandPracticesChapter1/2/3/7thus,r23=r12Significance?Foranefficientantireflectioneffect,wavesA(reflectedat1-2)andB(reflectedat2-3)inFigure1Q4belowshouldinterferewithnear“totaldestruction”.Thatmeansthey

4、shouldhavethesamemagnitudeandthatrequiresthatthereflectioncoefficientbetween1and2shouldbethesameasthatbetween2and3;r12=r23.Thus,thelayer2canactasanantireflectioncoatingifitsindexn2=(n1n3)1/2.Thiscanbeachievedbyr12=r23.Thebestantireflectioncoatinghastohavearefractiveindexn

5、2suchthatn2=(n1n3)1/2=[(1)(3.5)]1/2=1.87.Givenachoiceoftwopossibleantireflectioncoatings,SiO2witharefractiveindexof1.5andTiO2witharefractiveindexof2.3,bothareclose.ThephasechangeforwaveBgoingthroughthecoatingofthicknessdis2k2dwherek2=n2koandko=wavevectorinfreespace=2p/l.T

6、hisshouldbe180°orp.Thusweneed2n2(2p/l)d=porSolutionsforOptoelectronicsandPhotonics:PrinciplesandPracticesChapter1/2/3/7ForSiO2d=l4n2=900´10-9m4(1.5)=0.15mmSolutionsforOptoelectronicsandPhotonics:PrinciplesandPracticesChapter1/2/3/7ForTiO2d=l4n2=900´10-9m4(2.3)=0.10m

7、mSolutionsforOptoelectronicsandPhotonics:PrinciplesandPracticesChapter1/2/3/71.8Thinfilmcoatingandmultiplereflections:Assumethatn1

8、wherelisthefreespacewavelength.Thewavehastobemultipliedbyexp(-jf)toaccountforthisphasedifference