Slides Chapter IV - Bo Thu Quang

7/30/2019 Slides Chapter IV - Bo Thu Quang

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NHM SV THC HIN: Phm Xun Trung 20092890VVnS 20093600

Hong S Chnh 20090316Nguync Ti 20092299

VIN IN T VIN THNG TRNG I HC BCH KHOA H NI K54


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I. Gii thiu chung

II. Tng quan v Photodiodes

III. So snh cc loi Photodiodes

IV. Nguyn l hot ng ca b thu quang


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I. GII THIU CHUNG

3

Thng tin quang:L mththngtruyn thng tin qua si quang.Thng tin cchuynthnh nh sng v sau nh sng c truyn qua si quang, tininhn n cbini thnh thng tin nh ban u.

Cc thnh phn chnh ca tuyn truyn dn cp si quang


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I. GII THIU CHUNG

4

Nhvy, tuyn thng tin quang gm: Thitb pht quang

Thitbchuyniinquang E/O

Thitb thu quang Thitbchuyni quang - in

Ngoi ra cn mts thnhphn: B ghp ni quang (Connector) Cc mi hn B chia quang

Cc trmlp Bkhuchi quang Thitb tn sc Trm xen r knh


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I. GII THIU CHUNG

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Trong h thng thng tin quang, b thu quang l mttrong nhngthitb quan trngnht.

Tib thu quang, tn hiu quang t pha pht i ticbini thnh tn hiuin, rickhuchivphchitrli thnh tn hiu cng dng ban u.

Thnhphncab thubini quang inthnggm2 loi l:b tch sng photodiodes PIN v photodiodesthc lAPD.

Thct,b thu quang l thitb quang trngnht trong

cc h thng truyndn quang. c ng truyndn di vi tc bit ln, b thuquang cntha mn 2 yu cu quan trng: Ts SNRln, nhy thu cao v hotngc trong iukin c bngtnln.


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2.1 it PINCu toPhn b in trngp ng tn s

2.2 it thc l (APD)Cu toNguyn l lm vic


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7

P

I

N

Lp chng phn x

Cch in (Sio2)

Vng tip xc(kim loi)

Tip xckim loi

nh sng

Cu to diode thu quang PIN

Cu to:Mt lp bn dn n+Mtlptdn I: khng pha tp,hoct lp p.

Cu trc c bn ca PIN:

Gm cc vng bn dn p, n gia lmt lp t dn i rt mng. Khi diodePIN c phn cc ngc th diodekhng c dng, ch c dng ngcrtnhgi l dng ti. Khi nh sng ivo photondiode nu mt photon sinhra ti lp p, i, n mtcpin t v ltrng. Cc int thb ht vmin nv c in p dng, cn cc l trngth v pha min p c in p m nhintrng ngoi.

Hnh nhthc


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8

S vng nng lng ca photodiode PIN

Qu trnh pht ra cc cp in t v l trng cn gi l ht mang quang.


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Min n

Vng dn

in trng

Nn

glng

Vng nghoin t

L trng

9

S vng nng lng ca photodiode PIN


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10

Lung dng to ra trn tigi l photo, tns v cng dng nyphthuc vo nh sng u vo. Tuy nhin di ca xung nh sng a vophilnhnthi gian tri td cnthit ccphnt mang inchyqua vng tri virng d (trong min i).

Cc tham s quan trng:

Mimt Photodiodes c 1 hiusutlngt ring. ilng ny ctnh nh sau:

hP

eI

in

p

/

/

S cc cp in t - l trng c pht ra

S cc photon i ti

Tham sth 2 quan trng l hschuyni dng photon R:

h

e

P

IR

in

p


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Nguyn l:

Khi diot c phn ccngc c gi tr ln, minin tchkhng gian chuyntip Pi v Ni sn su v pha i timc hai min

ny chm vo nhau v nhvyhunhchiu dy camin i l rngcaminin tch khng gian chuyntip PN.

Chiu dy min bazo caiot ny lm rtmng sao cho hunhtonbshpth ring chxy ra trong min i.

Nhvy thi gian di chuynca cc htdn thiusmicpht x do hpth as ch tnhbngthi gian cun cc htdnyiqua min i. T cc nhctnsgiihn.

11

Nguyn l hot ng


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12

Tcpng:

Tcpng do cc yut sau yquytnh: Skhuch tn htdn

Thi gian sngcahtdn trong lp ngho in dung calp ngho Nuhtdn sinh ra ngoi lp ngho rikhuch tn

vo lp ngho th thi gian trslnngha l tcpngnh.

gimthi gian trlpchuyntip p-nphicto nn rtgnbmtmu.

Phn ln photon s c hp th trong lp nghonulp ngho dy.


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13Cu trc ca APD v in trng vng tri

Cu trc gmlp bn dn p, n v lp bn dnyu p - n+ cn gi l minthc, cngintrng trong min ny rtln,yxy ra qu trnhnhn int.

Cu trc:


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14

Nguyn l lm vic ca APD:

nh sng i vo thitb xuyn qua vng Pt v chpth trongvng vt l i, khi c photon bhp th n s truynnng lng chointto ra cc cpint - l trng v chng b tch di tcngcaintrng trong vng i.

Cc in t ny qua vng i n min p-n+ th chng nhn thmnnglng do intrngmnhtiy.Nnglng thm ny mnhnmc cc int khi va chm vo cc nguyn tlito ra ccphnt mang inmigi l ion ha do va chm.

S lng cc phn t mang in tng nhanh, dng in sinh rackhuchinhiu ln so vi PIN, do nhycngtng ln.ivi photodiodes Sc, ngngin trngcn thit thu nhnmc 105 V/cm.


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So snh PIN v APD:

Hai loi diode quang PIN v APD uc phn ccngc, khi khngc nh sng th ch c dng tri rtnh. Khi c nh sng vo, dng ny tngtuyn tnh vi dng nh sng v cng sutbcx. Dng ny gy trn timtin p a vo khuchi cho ra mt tn hiu nguyn thy.

Diode PIN c tp m ninh, song khng c khnngkhuchi dng innn khng nng cao nhy my thu c.Ngcli diode APD c tp mnilnnhng c khnngkhuchi dng in nn nng cao nhy, songdiode Ge-APD li c tp m niln, nn hnch cng sut thu tithiu cho

php.

Cc diode PIN chhotngvitc bit khng lnn vi ba trm Mbit/s,cn APD c thhotngvitc bit ti hng Gbit/s. Diode PIN cnin p cung cpnh, ngcli APD cnin p cung cp

ln hng trm volt, c tnh lm vicca APDphthuc vo nhitnhiudo cnsdngngun p iuchnhnhit, nn chi ph tng.


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Nguyn l cbn

B thu quang c chcnng chnh l bini tn hiu quang thu cthnh tn hiu in, rikhuchi v hiphc tr li thnh tn hiu

cng dngu vo thitb pht quang.Bbin i quang in thng l b tch sng photondiode. Trong

thng tin quangb tch sng quangphitha mn yu cuvnhythu cao, tc nhanh, tp m thp vbc sng hotng ph hp.

Nhngb tch sng quang bn dncsdng l v c kch thcnh, vtliu ph hp, nhy cao, thi gian png nhanh.


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PD

RL

B thu quang

h

vQuytnh

Clock

Ext

Tinkhuch

ikhuch

ichnh

Tn

hius ra

Clock

ra

Cu hnh ca b thu quang s tiu biu

B bin i quang in: L b tch sng photodiode bin i cngsut quang thu c thnh dng in ti u ra

Nhim v:B thu quang phi m bo thu c tn hiu rt yu,bmo v phi tch c thnh phn nhiu kh ln so vi tn hiu

B tch sng quang

B khuch i in

Mch x l tn hiu

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Thitb thu quang hayb thu quang l mt trong cc thitb quan trngnht v n sau cngcatchchthngtruyndn, ni thu nhnmic tnh tc ng trn ton tuynati. Vvyhotngca n lin quan trctiptichtlng tonbhthngtruyndn.

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Cutob thu quang

Photodiode:bini cng sut quang thnh tn

hiu dng inBtinkhuchibini dng thnh tn hiu

in p ph hpvi cc mch sau.Bkhuchi chnh: Tiptckhuching

thi tiuchnhmcin p mbomc rannh,blisbiniin do cc khu trcgy ra.

B cn bng: B li sbiniv bin vphaB lc: Lm gim mc nhiu cab tch

sng,bkhuchi tc ng vo tn hiu.Mch tch ng h: ng h c tch ra t

dng shiu v sdng ti sinh li dng s

hiu trong mchquytnh.Bquytnh

Ai Kchnh Bng

CnLc

nh

Quyt

C.K


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Cc thng scbn:nhy thu quang:

nhy thu quang cho bitkhnngbini cng sutquang thnh dng in. Nu ti mtbc sng c s

photon n l N0 v nng lng mi photon E= hc/ th

cng sut quang thu c:t

QdNdchP.

...0

Tp m trong b tch sng:Tiu thu th tl tn hiutp m, Trongb thu quang,tp m xuthin l do qu trnhbini photon thnh cc

int v tp m nhitt cc mchkhuchi tn hiu.


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Thi gian png:Thi gian pngca photodiode vimchu vo chyu

phthuc cc yut sau:- Thi gian chuyndch cc ht mang photon trong vng tri.- Thi gian khuch tn cc ht mang photon ra bn ngoi vngtri.- Hngsthi gian RC ca photodiode v cc mchin linquan ca n.

- Tc p ng ca photodiode cbnb gii hn do thigian to ra cc ht mang pht photon di chuyn qua vngtri.Thi gian dchchuyn tdphthuc vo vntc tri ht mang

Vd v rng vng tri td = W/Vd. 20

Cc thng scbn:


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Ts tn hiu trn nhiu SNRtng qut cho c PIN v APD:

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Cc thng s c bn:

2

2

PISNR Cng sut tn hiut dng photo

Cng sutnhiub tch sng + C/S nhiubK

Trong : 2 l cng sutnhiutng

So snh SNR ca 2 loi Photodiodes:

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.

e

in

e

in

PIN Bh

P

eB

PRSNR

Ae

in

Ae

in

APD FBh

P

FeB

PRSNR

22

.


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Cc ngunli trong b thu quang: Qu trnh tch sng cab thu quang chunhhng

canhiungunnhiu khc nhau. Cc ngun ny c th l: t ngoi hthngnhnhiu

kh quyn, nhiu ca thit b no , hoc t bntrong hthng.

Nhiunhit v nhiulngt l trinht trong b thu- Nhiunhit.

- Nhiulngt.


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Cc tham snhhngnnhy thu Gii hn lng t trong b tch sng quang.

nhngha: Hon ton c th tm ra c cng sutquang thu nhnhtc yu cuivi cc thng s

c tnh tsli bit trong hthng.

Tsphn bit:c xc nhbitsgia cng sut P1trng thi

m v cng sut P0trng thi ng (ngt):

0

1

P

PR

ext


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Tukhuytimcasidn quang, ngdngca n vo truyndnrtadng. Tuy nhin ty khong cch gia my pht v my thu, dunglng, tctruyndn m chnloisi cho ph hpvituyn.

ivi thitb pht quang, nuc ly truyndnngn, tc thp vtrung bnh th sdng LED pht xcnh v gi thnh thp, tin cy cao,cng sut pht t 5mW n 10mW, rngphln. Vituyntruyndn

c ly di, tc cao th phisdng diode lasern mode v n c phhp, cng sut ghp vo siln, cbit DFR c nnhnhit cao, sdngiubintrctip.

Trong h thng truyndn dung lng ln v tc cao, pngnhu cu, hin nay ngi ta thngsdngkthut ghp knh quang phn

chia theo thi gian OTDM v ghp knh quang phn chia theo bc sngDWDM.B THU QUANG NG VAI TR QUAN TRNG, NGY MT

C CI TIN V TT C CC THAM S, P NGNHNGYU CU NGY CNG CAO.

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CM N

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