ec2402 optical qb 2bsub

8/16/2019 Ec2402 Optical Qb 2bsub

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Subject: Optical Communication and Networking Subject code: EC 2402Class: VII SEM ECE

UNIT I INTRODUCTION

Introduction, Ray theory transmission- Total internal reflection-cce!tance an"le #

Numerical a!erture # S$e% rays # &lectroma"netic mode theory of o!tical !ro!a"ation #

&' %a(es # modes in )lanar "uide # !hase and "rou! (elocity # cylindrical fibers # S'

fibers*

PART-A+ multimode ste! inde fiber %ith a core diameter of ./ 0m and a relati(e inde difference

of +*12 is o!eratin" at a %a(elen"th of /*.1 0m* If the core refracti(e inde is +*3.

determine 4U !ril5'ay 6/+/

4a Normali7ed fre8uency of fiber*

4b The number of "uide modes*

V= (2πa!" n# (2$"#2 =%&'%&4M= V22 = 2)%2

6 Define the numerical a!erture of a ste! inde fiber* 4U !ril5'ay 6//1 9 6/+/

It i* t+e relation*+ip ,etween t+e acceptance angle and t+e -I o. t+e t+ree media in/ol/ednamel core1 cladding and air' +e N3 i* a dimen*ionle** uantit1 w+ic+ i* le** t+an unitwit+ /alue* ranging .rom 0'#4 t0 0'&0' N3 = (n# 2 5 n2 2" 6

'ention the major ad(anta"es of o!tical fiber communication system o(er micro%a(e

communication system* 4U No(5Dec 6/+/

• Small *i7e and weig+t

• Electrical i*olation

• Immunit to inter.erence and cro** talk

• Signal *ecurit and low tran*mi**ion lo**• -uggedne** and .le8i,ilit

• S*tem relia,ilit and ea*e o. maintenance

3 'ention the ad(anta"es and disad(anta"es of monomode fiber o(er multimode fiber*

4U No(5Dec 6/+/ U !r5'ay;6//. R-6//3

Single mode .i,er *u*tain* onl one mode o. propagation' Multimode .i,er contain*+undred* o. mode*'d(anta"es of monomode fiber9#' Monomode .i,er i* .ree .rom inter modal di*per*ion2' :ig+er ,andwidt+ i* po**i,le in monomode .i,er'Disad(anta"es of 'onomode fiber9#' Onl ;3SE- optical *ource +a* to ,e u*ed w+ic+ i* co*tl t+an ;E< *ource'2' Smaller core radii pre/ent* ea*ier launc+ o. optical power in to t+e .i,er'

1 Define acce!tance an"le and critical an"le for fiber* 4U !r5'ay6//


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? @hat is tunnel effectA 4U No(5Dec 6//


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+ere V = (2πaλ" (n# 2 5 n2 2" 6

+3 Consider a !arabolic inde %a(e-"uide %ith n+ > +*B1, n6 > +*?BB and core radius 61

micrometer* Calculate the numerical a!erture at the ais and at a !oint 6/ micrometer from

the ais* 4U No(5Dec 6//1

Ji/en n# = #'%&1 n2 = #'%%1 a= 2&Fm1 Numerical aperture at t+e a8i* N3 (0" = n# (2$" #2

$= (n#@n2" n#= (#'%&@#'%%"#'%&=0'04#%# N3 (0" =#'%& (20'04#%#"#2=0'&0&4 N3 (20 Fm" = N3 (0" ?(#@(ra"2=0'&0&4?(#@(202&"2=0'AA24'

+1 It is desired to ma$e a sin"le #mode fiber at an o!eratin" %a(elen"th > +// nm %ith n core>+*1/1 and nclad > +*1/6* Eind the numerical a!erture and core radius*

4U No(5Dec 6//?

mnm

NA

V a

nn NA

µ π π

λ 2'&

0&'0

40&'2

2

#A00

2

0&'0&02'#&0&'# 22222

#

===

=−=−=

+?Fi(e the refracti(e inde e!ression for "raded inde fiber* 4U No(5Dec 6//?

( ) ( )

≥=∆−≈∆−

≤≤

∆−

=

a forr nnn

ar for a

r n

r n

2#

2#

#

2#

#

#2#

02#"(

α

+B @hat is meant by mode cou!lin"A @hat causes itA 4U No(5Dec 6//?

Mode coupling re.er* to interaction o. +ig+er order mode* in t+e core medium wit+t+e radiation mode* in t+e cladding' :armonic /ariation o. +ig+er order mode re*ult* w+en t+emode tra/el* t+roug+ t+e core and it undergoe* e8ponential deca in t+e ,oundar w+ic+ interact*

wit+ t+e radiation mode and re*ult* in mode coupling'Koundar condition n2 kL Ln# k'+. !oint source of li"ht is +6 cm belo% the surface of a lar"e body %ater 4n>+** @hat is

the radius of the lar"est circle on the %ater surface throu"h %hich the li"ht can emer"eA

4U No(5Dec 6//3 ,No(5Dec 6//1

n# *inB#= n2 *inB2n#=#'AA1*inB#=#2#0@28#'AA(#2#0@28" =#8=# cm'

+


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n#(# 5 2 ∆ " 6 = n2 .or r ≥a

+ere PrQ radial di*tance .rom t+e .i,er a8i* a @ core radiu* n# 5 - # o. t+e core1 n2 5 - 2 o. t+e cladding

6/ Fi(e the relationshi! bet%een rays and modes* 4U No(5Dec;6//B R-6//3

'odes9 Hropagation o. lig+t wa/e* along t+e wa/e guide de*cri,ed in term* o. *et o.

guided electromagnetic wa/e* i* called mode' Eac+ guided mode i* a pattern o. electric andmagnetic .ield line* t+at i* repeated along t+e .i,er at inter/al* eual to wa/elengt+

Ray con"ruence9 3 lig+t ra can ,e a**ociated wit+ an plane wa/e t+at i* perpendicular to t+e p+a*e .ront o. t+e .amil o. plane wa/e* corre*ponding to a particular mode .orm* a *eto. ra*'

Gor a monoc+romatic lig+t .ield o. radian .reuenc R a mode tra/elling in po*iti/e 7direction i* gi/en , e (Rt@7"'@ 7 component o. wa/e propagation con*tant'

6+ @hy do %e !refer ste! inde sin"le mode fiber for lon" distance communicationA

Step inde8 *ingle mode .i,er +a* a" low attenuation due to *maller core diameter ," +ig+er ,andwidt+ and c" /er low di*per*ion'

66 Define relati(e refracti(e inde difference*+u* relati/e re.racti/e inde8 di..erence i* t+e ratio ,etween t+e re.racti/e inde8 di..erence (o. coreand cladding" and re.racti/e inde8 o. core'

6 @hat is Snell;s la%A

+e relation*+ip at t+e inter.ace i* known a* Snell>* law and i* gi/en , n#*inT#=n2 *inT2 63 @hat is the necessity of claddin" for an o!tical fiberA

a" o pro/ide proper lig+t guidance in*ide t+e core ," o a/oid leakage o. lig+t .rom t+e .i,erc" o a/oid mec+anical *trengt+ .or t+e .i,erd" o protect t+e core .rom *cratc+e* and ot+er mec+anical damage*

61 mon" micro%a(e and li"ht %a(es %hich ha(e hi"h bit rate distance !roductA @hyA

;ig+t wa/e* +a/e +ig+ ,it rate di*tance product ,ecau*e lig+t wa/e* +a/e +ig+ .reuenc(#0#4 :7" t+an microwa/e .reuenc(#0## :7" and in.ormation carring capacit o. an electromagneticwa/e i* directl proportional to it* .reuenc'6? 'ention the ad(anta"es of "raded inde fiber*

(a" Signal di*tortion i* low ,ecau*e o. *el. .ocu*ing e..ect'(," K' i* .rom 200 M:7 to 00 M:7(c" 3ttenuation i* le**(d" Numerical aperture i* le**6B @hat is the condition for TIRA

(a" ;ig+t *+ould tra/el .rom den*er medium to rarer medium'(," +e angle o. incidence *+ould ,e greater t+e critical angle o. t+e den*er medium

6. Define -number*It* de.ined a* t+e normali7ed .reuenc o. t+e .i,er gi/ing t+e cuto.. wa/elengt+ condition and

t+e relation .or num,er o. mode* propagating t+roug+ t+e .i,er'6


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Material di*per*ion ari*e* .rom t+e /ariation o. re.racti/e inde8 o. core material a* a.unction o. wa/elengt+' +i* cau*e* wa/elengt+ dependence o. group /elocit o. an gi/en mode'Hul*e *preading occur* e/en w+en di..erent wa/elengt+ .ollow t+e *ame pat+'2' @a(e"uide dis!ersion9

a/eguide di*per*ion occur* ,ecau*e a *ingle mode .i,er onl con.ine a,out )0Y o. optical power to t+e core ' 3*3 ! ! > /*?!4/ e-!7 > 1*/BQ+/-3@atts

? @hat is the need for mode cou!lin" in o!tical fiberA 4U !r5'ay6//


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• radiation lo**e*+ @hat do you mean by )olari7ation mode dis!ersionA 4U No(5Dec;6//B,R-6//3


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3ttenuation U= 0log

#

P

P

L

i

= o

i

P

P log

&'A

#

= 0'&&

;o**=0'&&A'&=#' +//nmA

4U !r5'ay 6//?

Gi,er ,ire.ingence K. = n@n8 = (!; p"+en ; p= #0 cm1 K. = (#A00 #0@ #0#0@2" = #A0#0@%

+en ; p= 2 cm1 K. = (#A00 #0@ 2#0@2" = &0 #0@%

66 ist the different ty!es of mechanical misali"nments that can occur bet%een t%o joined

fibers 4U No(5Dec;6//B R-6//3

• ;ateral mi*alignment• ;ongitudinal mi*alignment

3ngular mi*alignment

6 Calculate the ratio of stimulated emission rate to the s!ontaneous emission rate for lam!

o!eratin" at a tem!erature of +/// M* ssume a(era"e o!eratin" %a(elen"th /*1 micrometer*

4U 'ay5Lune 6//?

4-e.er page num,er 2)) o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition"

63 Name fe% s!licin" methods in fiber o!tics* 4U No(5Dec 6//?+e di..erent .i,er Splicing tec+niue* are• Gu*ion *plicing• V groo/e and tu,e mec+anical *plicing• Ela*tic tu,e *plicing• -otar *plicing

61 @hat are s!licesA @hat are the re8uirements of s!licesA

+e *plice* are generall permanent .i,er oint*1 w+erea* connector* are temporar .i,er oint*'Splicing i* a *ort o. *oldering' +e reuirement* o. *plice* are9

S+ould cau*e low attenuationS+ould ,e *trong \ lig+t in weig+t

] *+ould +a/e minimum power lo**S+ould ,e ea* to in*tall

6? Define Ralei"h scatterin" loss*

It>* t+e dominant lo** mec+ani*m in t+e ultra/iolet region' It* tail e8tend* upto in.raredregion' It* in/er*el proportional to t+e .ourt+ power o. wa/elengt+' It ari*e* due to t+emicro*copic in+omogenetie* cau*ed , den*it .luctuation*1 re.racti/e inde8 .luctuation* andcompo*itional /ariation*'

6B Define 'ie scatterin" loss


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It>* a linear *cattering w+ic+ ari*e* .rom t+e in+omogenitie*1 w+ic+ are compara,le in *i7eto t+e guided wa/elengt+1 in t+e .orward direction' It* al*o due to t+e imper.ect clindrical*tructure o. t+e wa/eguide1 irregularitie* in t+e core@cladding inter.ace1 core@cladding re.racti/einde8 di..erence along t+e .i,er and diameter .luctuation*' It can ,e reduced , de.ect .ree .i,er.a,rication and increa*ing t+e relati/e re.racti/e inde8 di..erence'

6. Jo% are micro-bendin" losses reducedA

+e*e are t+e lo**e* due to t+e ,end* in t+e .i,er a8i*1 during ca,ling and *tre** acting on

t+e .i,er' +e*e produce mode coupling and radiation lo**e*' +e*e can ,e reduced , e8truding acompre**i,le acket o/er t+e .i,er' +en e8ternal .orce* are applied1 t+e acket will ,e de.ormed ,ut t+e .i,er will tend to *ta relati/el *traig+t'

UNIT III SOURC&S ND D&T&CTORS

O!tical sources: i"ht &mittin" Diodes - &D structures - surface and ed"e emitters, mono

and hetero structures - internal - 8uantum efficiency, injection laser diode structures -

com!arison of &D and ID O!tical Detectors: )IN )hoto detectors, (alanche !hoto

diodes, construction,

Characteristics and !ro!erties, Com!arison of !erformance, )hoto detector noise #Noise

sources, Si"nal to Noise ratio, Detector res!onse time*

PART-A+ lens cou!led surface emittin" &D launches +


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Hout = 2 m (gi/en"` = poutpin = 0'0#

? Define three modes of ca(ity* 4U No(5Dec 6//


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+3 Define res!onsi(ity* 4U No(5Dec 6//1 , 6//3,6//. 9 6/+/, !ril5'ay 6//1 96/+/

+e re*pon*i/it i* de.ined a* t+e ratio o. output p+otocurrent to t+e incident optical power' -=Ip Ho

+ere Ip@ a/erage p+otocurrent generated , a *tead a/erage optical power ' Hoincident on a p+oto detector

+1 Define the 8uantum efficiency of a !hoto detector*

4U No(5Dec 6//396//1, !ril5'ay 6/+/

uantum e..icienc ` i* t+e num,er o. electron +ole pair generated per incident p+oton o. energ +b i* gi/en ,

No' o. electron +ole pair* generated I p ` = @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ = @@@@@@@ No' o. incident power Ho +b

+? In a +//ns !ulse, ?+/? !hotons at a %a(elen"th of +// nm fall on an InFas

!hotodetector*On the a(are"e, 1*3+/? electron hole !airs are "enerated* Eind the 8uantum

efficiency* 4U No(5Dec 6/+/

-e.er e8ample '2 (HJ NO924% in Ard edition Jerd Xei*er"

` = (No o. electron@+ole pair* generated" (no o. incident p+oton*" &'4#0(#0" 0'

+B silicon a(alanche !hotodiode has a 8uantum efficiency of ?12 at a %a(elen"th of


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Eg=+=+c!'+='2&#0@A4 [@*'c=A#0) m*'!= +c Eg='2&#0@A4A#0)2'20)#0@#=)'%&%#0@%'!=)'%&%#0@% m'

66 Com!are the !erformance of )D and )IN diode* 4U No(5Dec 6//.

-e.er ta,le @#' Hage No9 2%6 Define 8uantum limit* 4U No(5Dec;6//B R-6//3

+e minimum recei/ed optical power reuired .or *peci.ic ,it error rate per.ormance in adigital **tem i* known a* uantum limit'

63 @hat are the desired features of a !hotodetectorA 4U No(5Dec;6//B R-6//3

• :ig+ re*pon*e• Minimum addition o. noi*e• Ga*t re*pon*e *peed• Su..icient ,andwidt+• In*en*iti/e to /ariation in temperature'

61 @hat is meant by 8uantum limitA 4U 'ay5Lune 6//?

+e minimum recei/ed optical power reuired .or a *peci.ic ,it error rate per.ormance in adigital **tem i* known a* t+e uantum ;imit'

6?n )D "enerates a current of +// n %hen the incident !o%er is 1 n%* The o!eratin"

%a(elen"th is +*1 micro meter* Eind its re!onsi(ity* If the 8uantum efficiency is /*B, find the

multi!lication factor* 4U No(5Dec 6//?

2&

4

#00

4#0EAE#0EC2&'C

#0E&E#0E&'#E#0EC'#E%'0)A4

C#

0

===

=== −−−−

nA

nA

I

I tionfactor Multiplica

nA P h

q I

P

M

P ν

η

6B "i(en )D has a 8uantum efficiency of ?12 at a %a(elen"th of


13/26

/ Define radiance* 4U No(5Dec 6//3

-adiance i* t+e optical power radiated into a unit *olid angle per unit emitting *ur.ace areaand i* generall *peci.ied in term* o. watt* per *uare centimeter per *teradian' Since t+e optical power t+at can ,e coupled into a .i,er depend* on t+e radiance (i@e1 on t+e *patial di*tri,ution o. t+e optical power"1 t+e radiance o. an optical *ource rat+er t+an t+e total output power i* t+eimportant parameter w+en con*idering *ource to .i,er coupling e..iciencie*'

+ Define modal noise and mode !artition noise* 4U !ril5'ay 6//< 9 6/+/

'odal Noise: Inter.erence o. a multimode optical communication* .i,er wit+ a la*er lig+t w+en a*peckle pattern in t+e lig+t inten*it in t+e .i,er alter* ,ecau*e o. motion o. t+e .i,er or c+ange* int+e la*er *pectrum' 3l*o known a* modal di*tortion'

'ode !artition noise: In an optical communication* link1 p+a*e itter o. t+e *ignal cau*ed , t+ecom,ined e..ect* o. mode +opping in t+e optical *ource and intramodal di*tortion in t+e .i,er'

6 @hat is meant by modal noiseA 4U !ril5'ay 6//1, !ril5'ay 6//B

Modal noi*e ari*e* w+en lig+t .rom a co+erent la*er i* coupled into a multimode .i,er' +i*i* generall not a pro,lem .or link* operating ,elow #00 M,p* ,ut ,ecome* di*a*trou* at *peed*around 400 M,p* and +ig+er' +e .ollowing .actor* can produce modal noi*e in an optical .i,er

link • Mec+anical di*tur,ance* along t+e line• Gluctuation* in t+e .reuenc o. an optical *ource

Differentiate &Ds and aser diodes*

&D aser diode

+e output o,tained i* inco+erent' +e output o,tained i* co+erent';e** e8pen*i/e and le** comple8 More e8pen*i/e and more comple8';ong li.e time' ;e** li.e time'

3 'Define !hotocurrent'+e +ig+ electric .ield pre*ent in t+e depletion region cau*e* t+e carrier* to *eparate and ,e

collected acro** t+e re/er*e@,ia*ed unction' +i* gi/e* to a current .low in t+e e8ternal circuit1 wit+one electron .lowing .or e/er carrier pair generated' +i* current .low i* known a* p+otocurrent1 Define im!act ioni7ation'

In order .or carrier multiplication to take place1 t+e p+oto generated carrier* mu*t tra/er*e aregion w+ere a /er +ig+ electric .ield i* pre*ent' In t+i* +ig+ .ield region1 a p+oto generated electronor +ole can gain energ *o t+at it ioni7e* ,ound electron* in t+e /alence ,and upon colliding wit+t+em' +i* carrier multiplication mec+ani*m i* known a* impact ioni7ation'? Define a(alanche effect*

+e newl created carrier* are accelerated , t+e +ig+ electric .ield1 t+u* gaining enoug+ energto cau*e .urt+er impact ioni7ation' +i* p+enomenon i* called a/alanc+e e..ect'B @hat is ! ! n reach- throu"h structureA

+e reac+ 5t+roug+ a/alanc+e p+otodiode (-3H


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+e p+oto detector mu*t +a/e a +ig+ uantum e..icienc to generate a large *ign al power' ]+eampli.ier noi*e* *+ould ,e kept a* low a* po**i,le'3/ @hat is meant by error rateA

3n approac+ i* to di/ide t+e num,er Ne o. error* occurring o/er a certain time inter/al t , t+enum,er Nt o. pul*e* tran*mitted during t+i* inter/al' +i* i* called eit+er t+e error rate or t+e ,iterror rate'

Kit error rate KE- =Ne Kt +ere K= #,3+ @hat is meant by ecess noise factorA

+e ratio o. t+e actual noi*e generated in an a/alanc+e p+otodiode to t+e noi*e t+at would e8i*t i.all carrier pair* were multiplied , e8actl m i* called t+e e8ce** noi*e .actor (G"'36 Define multi!lication '*

+e multiplication M .or all carrier* generated in t+e p+otodiode i* de.ined , M = IM IHIM a/erage /alue o. t+e total multiplied output current

IH primar un multiplied p+otocurrent

3 @hat are the characteristics of li"ht sourcesA

(a" +e *pectral line widt+ o. t+e *ource *+ould ,e a* *mall a* po**i,le ,ecau*e di*per*ion i*directl proportional to it'

(," It* *i7e and con.iguration *+ould ,e compati,le wit+ t+e launc+ing lig+t and +ig+ldirectional

(c" It mu*t accuratel track t+e electrical input *ignal to minimi7e di*tortion and noi*e(d" It *+ould ,e capa,le o. *imple *ignal modulation o/er a wide K'(e" It mu*t couple *u..icient optical power to o/ercome attenuation

33 @hat is meant by diffusion len"thA

3* t+e c+arge carrier* .low t+roug+ t+e material o. a HIN p+otodetector due to p+oto1 *omeelectron@+ole pair* will recom,ine and +ence di*appear' +e c+arge carrier* mo/e a di*tance ;n or; p .or electron* and +ole* re*pecti/el' +i* di*tance i* called di..u*ion lengt+'31 Define transit time*

It* de.ined a* t+e time taken to tran*.er t+e c+arge carrier* wit+in t+e depletion region' +ere*pon*e *peed o. a p+otodiode i* limited , t+e time it take* p+otogenerated carrier* to tra/elacro** t+e depletion region' +i* tran*it time td depend* on t+e carrier dri.t /elocit /d and t+edepletion laer widt+ w and i* gi/en ,1

td>%5(d3? !hotodiode is constructed of Fas %hich has a band"a! ener"y of +*3e at //M*

Determine the lon" %a(elen"th cutoff*

c>hc5&" = ('2&#0@A4"(A#0)"(#'4A#'#0@#"=)nm

UNIT I EIK&R O)TIC R&C&I&R ND '&SUR&'&NTS

Eundamental recei(er o!eration, )re am!lifiers, &rror sources # Recei(er Confi"uration #

)robability of &rror # Vuantum limit* Eiber ttenuation measurements- Dis!ersionmeasurements # Eiber Refracti(e inde !rofile measurements # Eiber cutoff @a(e len"th

'easurements # Eiber Numerical !erture 'easurements # Eiber diameter measurements*

PART-A+ ist the im!ortant re8uirements of an o!tical recei(er* 4U No(5Dec 6//?

It +a* t+e ta*k o. .ir*t con/erting t+e optical energ emerging .rom t+e end o. a .i,er intoan electrical *ignal1 and t+en ampli.ing t+i* *ignal to a large enoug+ le/el' +e KE- o. a opticalrecei/er *+ould ,e le**'

6 @hat are the benefits of transim!edance am!lifierA 4U !ril5'ay 6//B


15/26

• It +a* a wide dnamic range compared to t+e +ig+ 5impedance ampli.ier• D*uall little or no euali7ation i* reuired ,ecau*e t+e com,ination o. -in and t+e .eed,ack

re*i*tor - . i* /er *mall1 w+ic+ mean* t+e time con*tant o. t+e detector i* al*o *mall'• +e output re*i*tance i* *mall1 *o t+at t+e ampli.ier i* le** *u*cepti,le to pickup noi*e 1cro**

talk 1electromagnetic inter.erence etc• +e tran*.er c+aracteri*tic o. t+e ampli.ier i* actuall it* tran*impedance1 w+ic+ i* t+e

.eed,ack re*i*tor' +ere.ore1 t+e tran*impedance ampli.ier i* /er ea*il controlled and *ta,le'• 3lt+oug+ t+e tran*impedance ampli.ier i* le** *en*iti/e t+an t+e +ig+ impedance ampli.ier1t+i* di..erence i* u*uall onl a,out 2 to A dK .or mo*t practical wide ,and de*ign*'

@hat is meant by !re-am!lifierA @hat are the ad(anta"es of !re-am!lifierA

[email protected]* are t+e circuit* t+at are de*igned to ma8imi7e t+e recei/er *en*iti/it w+ile maintaininga *uita,le ,andwidt+ *ince t+e recei/er>* *en*iti/it and K' are dominated , noi*e *ource*' It*ad/antage* are9

(a" :a* low noi*e le/el and +ig+ gain(," :a* +ig+ K'(c" :a* +ig+ dnamic range(d" :a* +ig+ *en*iti/it to a/oid non@linearitie*

3 @hat are the dra%bac$s of hi"h im!edance am!lifierAIt produce* a large input -C time con*tant1 t+e .ront@end K' i* le** t+an t+e *ignal K'' +u*1t+e input *ignal i* integrated and euali7ation tec+niue* mu*t ,e emploed to compen*ate .ort+i*'

1 Define etinction ratio

It* de.ined a* t+e ratio o. t+e optical power in a 0 pul*e to t+e power in a # pul*e' Kia*ing t+e lig+t*ource *lig+tl on during a 0 time *lot re*ult* in a non@7ero e8tinction ratio 1' It* e..ect i* a power penalt in recei/er *en*iti/it'

? 6$m len"th of multimode fiber is attached to a!!aratus for s!ectral loss measurement the

measured out!ut (olta"e from the !hoto recei(er usin" the full 6$m fiber len"th is 6*+( at a

%a(elen"th of /*.1 micrometer* @hen the fiber is then cut bac$ to lea(e a 6$m len"th the

out!ut (olta"e increases to +/*B*Determine the attenuation !er $m for the fiber at a%a(elen"th of /*.1 micrometer and estimate the accuracy of the result*

Solution:

Ud,=#0(;#@;2"log#0(V2V#" =#0(#')"log#0(#0'%2'#" =A'& d, km@#

B Je-Ne laser o!eratin" at a %a(elen"th of /*? 0m %as used %ith a solar cell cube to

measure the scatterin" loss in a multimode fiber sam!le* @ith a constant o!tical out!ut

!o%er the readin" from the solar cell cube %as ?*+3 n*The o!tical !o%er measurement at

the cube %ithout scatterin" %as +1*. 0 *The len"th of the fiber in the cube %as

6*


16/26

='2(A)'44_400" (#2"

=0'A0


17/26

t+e *ame .i,er' 65 4%-$m* @hat is the !ea$ !o%er re8uired to maintain a fundamental

soliton of %idth 4TE@J' +/ !sA 4U No(5Dec 6//?

+e G:M pul*e widt+ and 0 are related , G:M=#'%A0'0= G:M#'%A= #0p*#'%A= &'% p*H peak =#(2&'%2"=#&'& m'

+/ Define Merr effect*

+e non@linearit in t+e re.racti/e inde8 o. an optical material i* known a* t+e Xerrnonlinearit' +i* nonlinearit produce* a carrier@induced p+a*e modulation o. t+e propagating*ignal w+ic+ i* called Xerr e..ect' In *ingle@wa/elengt+ link*1 t+i* gi/e* ri*e to *el.@p+a*emodulation (SHM"1 w+ic+ con/ert* optical power .luctuation* in a propagating lig+t wa/e to*puriou* p+a*e .luctuation* in t+e *ame wa/e'

++ Define fre8uency chir!in"

3* t+e p+a*e .luctuation* are inten*it@dependent1 di..erent part* o. t+e pul*e undergodi..erent p+a*e *+i.t*' +i* i* cau*ed , /aring inde8 c+ange re*ulting in /aring p+a*e c+ange'+i* lead* to Greuenc c+irping' In t+i*1 t+e ri*ing edge o. t+e pul*e e8perience* a red *+i.t in.reuenc and t+e trailing edge o. t+e pul*e e8perience* a ,lue *+i.t in .reuenc' Gre c+irping>*inten*it depend* on tran*mitted power'

+6 Define dynamic ran"e

+e per.ormance uantit o. intere*t i* de.ined a* t+e **tem dnamic range(* t+e point at w+ic+ t+e SKS ,ecome* pro,lem' It* appro8imation i*gi/en ,1


18/26

Ht+=2#(3e.. ,g ,;e.. "(#_/*ource/K"+? @hat are the schemes a(ailable for reducin" the !o%er !enalty effects of SKS

(a" Xeep t+e optical power per


19/26

Discuss the mode theory of !lanar %a(e-"uides also discuss !hase (elocity and "rou!

(elocityA 4U !ril5'ay 6//3, !ril5'ay 6//B 4-e.er page num,er 2@A0 o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition"3 Discuss the ray theory of transmission* 4U !ril5'ay 6//3

4-e.er page num,er #4@2A o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition"1 ist the ad(anta"es of o!tical fiber communication* 4U 'ay5Lune 6//?

4-e.er page num,er %@#0 o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2 nd

Edition"? Ste! #inde fiber has a normali7ed fre8uency 6?*? at a +// nm %a(e len"th* If core radius

is 61 0m find the numerical a!erture and mode (olume*

4U No(5Dec 6//?

Ji/en V=2'1!=#A00nm 1 a=2& m

CC)'2A2A"#0E#A00(

"#0E2&(EE2EE2

22'0#0E2&EE2C'2CE#A00

2"(

2

2C

2

2

A2#22

2#

===

===−=

−

−

−

π

λ

π

π π λ

a Modevolume

V a

nn NA

B &!lain %ith a neat bloc$ dia"ram the fundamentals of o!tical fiber communication*4. QQ

4No( 6//.

4-e.er page num,er &@% o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition". &!lain %ith a neat dia"ram the elements of an o!tical fiber transmission lin$*

4U No(5Dec;6//B,R-6//3

-e.er page num,er @#0 o. t+e ,ook POptical .i,er communicationQ , Jerd Xei*er1 A rd editionM: 2000'


20/26

0" multimode ste! inde fiber %ith a core diameter of ./ 0m and a relati(e refracti(e

inde difference of +*12 is o!eratin" at a %a(elen"th of /*.1 0m* If the core refracti(e inde

is +*3., estimate the normali7ed fre8uency for the fiber and number of "uided modes*

4U No(5Dec;6//BR-6//3

4-e.er page num,er 4 o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd Edition"

+3 Discuss the electroma"netic mode theory of o!tical !ro!a"ation 4U !ril5'ay 6//3

4-e.er page num,er 2A@2& o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition"

+1 Kriefly e!lain S' Eibers in o!tical communication 4'ay5Lune 6//


21/26

4-e.er page num,er ##0@## o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition"4iiThe beat len"th in a sin"le mode fiber is < cm %hen li"ht from an injection laser %ith a

s!ectral line %idth of +nm and a !ea$ %a(elen"th of +11/ nm is launched into it* Determine

the modal birefrin"ence and estimate the coherence len"th in this situation* lso, calculate

the difference bet%een the !ro!a"ation constants for the t%o ortho"onal modes and chec$

the result* 4/. 4U No(5Dec 6//


22/26

4-e.er page num,er )@ o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition"++ &!lain the effects o(er all si"nal dis!ersion in o!tical %a(e "uide* 4'ay5Lune 6//


23/26

4ii !hotodiode has a 8uantum efficiency of B2 %hen !hotons of ener"y +*1+/ -+< L are

incident u!on it* &stimate the %a(elen"th at %hich the !hoto diode o!erates and calculate

the incident o!tical !o%er re8uired to obtain a !hotocurrent of 6*6 0 %hen the !hoto diode

is o!eratin" as abo(e*4/? QQ

4-e.er page num,er 42 o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition"

6 Discuss the re8uirements of o!tical detector* 4U No(5Dec 6//34-e.er page num,er 420 o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition" Dra% the schematics of )IN !hotodiode and )D and e!lain* QQQ

4U No(5Dec 6//31 23v5Dec 6//?, !r5'ay;6//. R-6//3, No(5Dec;6//B R-6//3

-e.er page num,er 244 @ 2&2 o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rdedition M: 2000

3 Fi(en silicon )D has a 8uantum efficiency of ?12 at a %a(elen"th of


24/26

+/ Discuss the structure of ed"e emittin" and surface emittin" &Ds and e!lain* QQ

4U !ril5'ay6//3, No(5Dec 6//1

4-e.er page num,er A)@AA o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition" \-e.er page num,er #&0@#&A o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rdedition M: 2000

++ &!lain detector res!onse time of !hoto detectorAQQ 4U No(5Dec 6//


25/26

-e.er page num,er A#0@A## o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rdedition M: 2000

B Discuss %ith the aid of a suitable dia"ram the cut-bac$ techni8ue used for the measurement

of the total attenuation in an o!tical fiber* Indicate the differences in the a!!aratus utili7ed

for s!ectral loss and s!ot attenuation measurement* 4+?QQ

4-e.er page num,er %%@%)A o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition". Kriefly outline the !rinci!le behind the calorimetric methods used for measurement of absor!tion loss and scatterin" in o!tical fibers* 4+? QQ

4-e.er page num,er %)A@%) o. t+e ,ook Poptical .i,er communicationQ , [o+n' M' Senior1 2nd

Edition"


26/26

-e.er page num,er 4&@4 o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rdedition M: 2000

3 &!lain the %or$in" !rinci!le of o!tical CD' -e.er page num,er @ o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rdedition M: 2000

1 @rite short notes on ultra hi"h ca!acity net%or$* QQ

-e.er page num,er @ o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rd

edition M: 2000? &!lain ho% broadcast and select @D' net%or$ o(ercome limitation of SON&T net%or$A

-e.er page num,er 4%%@4)2 o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rdedition M: 2000

B &!lain ho% %a(elen"th routed net%or$s o(ercome limitation of broadcast and select @D'

net%or$A

-e.er page num,er 4)2@4)) o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rdedition M: 2000

. &!lain (arious nonlinear effect on o!tical net%or$ **

-e.er page num,er 4))@&02 o. t+e ,ook Poptical .i,er communicationQ , Jerd Xei*er1 A rd

edition M: 20004Note: &ach headin" may as$ in . mar$s 8uestions

ec2402 optical qb 2bsub

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