sfp op speed

8/12/2019 Sfp Op Speed

1/16

Created by: Imre Baumli 2010, IBM Advanced Technical

Support Techdocs, Copyright IBM

Corp.

1

OperationOperation speedspeed calculationcalculationfor 4Gb/sfor 4Gb/s SWSW andand LWLW SFPSFP

optical transceiversoptical transceivers

This document describes the channel operation speed, bit velocity

estimation, dispersion estimation as well as the SW and LW mini GBIC

operation speed calculation for4 Gb/s AVAGO SFP-Small Form-FactorePluggable parameters


2/16

5/1/2010 2010, IBM Advanced Technical


Corp.

2

ContentContent

Operation speed and the band width*

About Single Mode Fibers (Normalized Frequency, Polarization Mode Dispersion)

SW Avago 4 Gbps SFP optical transceiver operation speed calculation (=850 nm)

LW Avago 4Gbps SFP optical transceiver operation speed calculation (=1310 nm)

Observations


3/16



Corp.

3

Operation speed and band width

The channel operation speed - RR,, channel band width ((ff),), and the total dispersion ofthe optical line () are characterized by the following relationship: R = 2R = 2f=1/4f=1/4

The transmitter and receiver are characterized by a rise/fall time and the amplifier side of

the receiver is characterized by a band width , all these restrict together the speed of the

response, namely a the rise time on the output of the receiver.

The transmitter and receiver are characterized by a rise/fall time and the amplifier side ofthe receiver is characterized by a band width , all these restrict together the speed of the

response, namely a the rise time on the output of the receiver.

The total band width of the impuls in ps on the receiver output:

22 == ((trtr))22 ++ ((fiberfiber))22 ++ ((recrec))22 ++ ((aa))22

Where on the right part represent the transmitter, optical fiber, receiver and the echivalenta.a.

--trtr == ttrr/2/2 - transmitter impuls response width, whereris the optical rise time of the transmitter--

fiberfiber

is the total dispersion of fiber (in this case for SI-step index SMFs)

--recrec == recrec/2/2 - receiver impuls response width , whererecrec is the receiver rise time--aa = 1/8= 1/8ff the effect of the link distance of the receiver part is expressible with a echivalent-aa whereffis the channel band width from the receiver side in GHz


4/16



Corp.

4

trtr

recrec

LL fiberfiber

DPMD

trtr22

recrec22

f3dB = 0,35/rec

BrBr 0,1/ D0,1/ DPMDPMD(L)(L)1/21/2

D = c/BD = c/B2222LL

aa=1/8=1/8ff

fiberfiber22

22 = (= (trtr))22 + (+ (fiberfiber))22 + (+ (recrec))22 + (+ (aa))22 R = 1/4R = 1/4

Polarization Mode

Dispersioncoefficient

transmitter rise time

receiver rise time

length of fiber

bit velocity dispersion

total impulse width

operation speedoperation speed

Operation speed estimation block diagram


5/16



Corp.

5

About Single Mode Fibers

NAaa

V nn ==

22 22

2

1

NF value is: V ==== 2,405

Is the limit of the single mode operation.Is the limit of the single mode operation.

Base modes

HE11

TMTM0101

TETE0101

HEHE1111HHyybridbrid Electromagnetic ModesElectromagnetic Modes

TMTM0101 TransTransverseverse MagneticMagnetic ModesModes

TETE0101 TraTrannssverseverse Electric ModesElectric Modes

V

nn11--corecore

nn22--claddingcladding

nneffeff==KK

V=2.405V=2.405

Higher modesHigher modes

Single ModeSingle Modeoperation rangeoperation range

2

2

mod

VN es

The number of modesThe number of modes

Multi Mode operationrange

We can eliminate the higher modes using inequalityWe can eliminate the higher modes using inequality VV 2,4052,405 aa 2,405/22,405/2NANA

for SMF-Single Mode Fibers a 9 m (for LW fibers) and for cutoff 2a2aNANA /2,405 nm

Normalized frequency


6/16



Corp.

6

PolarizationPolarization ModeMode DispersionDispersion

TheThe theoreticaltheoretical sectionsection andand thethe realreal sectionsection ofofthethe opticaloptical fibersfibers

Real fiber is not completely symmetric.Real fiber is not completely symmetric. InIn casecase ofofthethe deformeddeformed fiberfibercorecore thethe rezultantrezultant polarizationpolarization

planesplanes fluctuatefluctuate inin aa rangerange,, becausebecause theythey propagatepropagate withwith differentdifferent velocityvelocity inin thethe planesplanes ((becausebecause ofof

thethe deformationdeformation)) andand theythey createcreate aa variablevariable opticaloptical powerpoweratat thethe endend ofofthethe fiberfibercorecore..

PMDPMD normalnormal delaydelay timetime

resultingresulting

polarizationpolarization planeplane

undeformedundeformed corecore

excentricexcentric ((deformeddeformed)) corecore

fluctuationfluctuation ofof

polarizationpolarization planesplanes

slowslow axisaxis

fastfast axisaxis

LDPMDPMD

kmpsPMD

/11,0 TheThe typicaltypical valuesvalues forforthethe DPMDDPMD polarizationpolarization modemode dispersiondispersion coefficientcoefficient areare::

Dr

PMD TL

11,01,0 = LDB PMDr /1,0

wherewhere TT isis thethe bitbit periodeperiode andand BrBrthethe bitbit velocityvelocity.


7/16



Corp.

7

SW Avago 4 Gbps SFP optical transceiver operation speed calculation

150 m/300 m150 m/300 mLength of the fiber - LL

850 nm850 nmOperating wavelength -

1,451,45Cladding refractive index n2

1,471,47Core refractive index n1>>>> n2

125125 mmCladding diameter ddcladdingcladding

5050 mmCore diameter - ddcorecore

ValueValueMultimodeMultimode fiberfibercharacteristicscharacteristics

AFBR-57D7APZ-IB, SW/150 or 300 mOptical transceiver type

PIN Photodiode5050 pspsReceiver electrical rise/fall time -recrec

Vertical Cavity Surface Emitting laserVertical Cavity Surface Emitting laser9090 pspsTransmitter optical rise/fall time -trtr

Laser typeLaser typeValueValueTransmitter and receiverTransmitter and receiver

characteristicscharacteristics

http://www.avagotech.com/products/optical_transceivers/storage/4http://www.avagotech.com/products/optical_transceivers/storage/4 g_fibre_channel/?linksource=dropdowng_fibre_channel/?linksource=dropdown

SW SFP device


8/16



Corp.

8

Two rays at entranceTwo rays at entrance

to fiberto fiberacceptanceacceptance

conecone

corecore nn11 >>>>>>>> nn22

MultiMulti--Mode FiberMode Fiber


L=150 mL=150 m

SingleSingle

impulseimpulse

Illustration of dispersionIllustration of dispersion

Rays at end of fiberRays at end of fiber

fastfast slowslow

Run time difference

For characterization of the size of dispersion the "run time difference" = 2-1 is the

suitable parameter.The run time difference is = (L= (Ln1/c)n1/c) where delta is the refractive index difference.For the above values the= 0,0013 = (L1= (L1n1/c)n1/c) = (150m(150m1,47/31,47/3108m/s)) 0,00130,0013 ===== 0,95 ns

Resultingfiber=0,95 ns 2fiber = (0,95)2 = 0,9025 ns =902,5 ps

Transmitter rise timetrtr = 90= 90 psps 2tr = (tr /2)2 = (45)2 = 2025 psReceiver rise timerecrec = 50= 50 psps 2rec = (rec /2)2 =(25)2 = 625 ps


9/16



Corp.

9

For 3dB bandwide correspondingrec is: f3dB = 0,35/rec = 0,35/5010-12 s =

==== 0,007103109 = 7 GHz

R = 2R = 2f=1/4f=1/4 a = 1/8f= 1/(87109)= (1/56) 10-9 = 0,017 ns

2a = 0,000289 ns = 0,000289103 ps = 0,289 ps

22 = (= (tr)tr)22 + (+ (rec)2 + (rec)2 + (fiber)fiber)22 + (+ (a)a)22 = 2025 ps + 625 ps + 902,5 ps + 0,289 ps =

==== 3552,789 ps = 59, 605 ps

R =1/4R =1/4 = 1/459, 605 ps = 1/(238,4210-12

)s = 0,00419 103

109

b/s = 4,194,19 Gb/sGb/s


10/16



Corp.

10

LW Avago 4Gbps SFP optical transceiver operation speed calculation

0,10,1

ps/(km)ps/(km)1/21/2PMD Polarization Mode Dispersion

coefficient- PMDPMD

4 km4 kmLength of the fiber - LL

1310 nm1310 nmOperating wavelength -

1,461,46Cladding refractive index n2

1,4651,465Core refractive index n1>>>> n2

125125 mmCladding diameter ddcladdingcladding

99 mmCore diameter - ddcorecore

ValueValueSingle modeSingle mode fiberfibercharacteristicscharacteristics

The mini GBIC (AvagoAvago, type, type:::::::: AFCTAFCT--57R5APZ, LW/4km57R5APZ, LW/4km) transmitter and receiver optical parametersare the followings:

www.avagotech.com/search/results.jsp?src=&siteCriteria=AFCT-57R5APZ

AFCT-57R5APZ, LW/4kmOptical transceiver type

PIN Photodiode5050 pspsReceiver electrical rise/fall time - recrec

High performanceHigh performance FabryFabry--PerotPerot9090 pspsTransmitter optical rise/fall time -trtr

Laser typeLaser typeValueValueTransmitter and receiverTransmitter and receiver

characteristicscharacteristics

LW SFP device


11/16



Corp.

11

LDLD PDPDcorecore nn11 >>>>>>>> nn22

SingleSingle--Mode FiberMode Fiber


L=4 kmL=4 km

PIN receiverPIN receiverFP laserFP laser

D(D())

Dispersion calculation

The run time of the rays (the time difference between the fast and slow rays at end of fiber) is::::::::======== DDLL The speed of light isThe speed of light is:: cc======== ff ff ======== c/c/ dfdf======== --(1/(1/22)) ccdd========1/1/22ccdd

======== DDLL ======== DD((22/c)/c) dfdf LL DD((22/c)/c) ff LL but the spectral wideff BB (bit velocity)======== DD((22/c)/c) BB LL

The run time is smaller as the bitThe run time is smaller as the bit periodeperiode


12/16



Corp.

12

BrBr 0,1/0,1/ DDPMDPMD(L)(L)1/21/2 for the Br- bit velocity resulting the following:

][50,02,0

1,0

21,0

1,0

][4]/[1,0

1,01,0

1010

12

12 spskmkmpsLBr

DPMD =====

D = c/B2D = c/B222L =L = =

=

++

kmnm

sm

kmnm

sm

4171610025,0

/3

4171610025,0

/3

10

1010

10

10212

26

212

8

kmnm

ps

kmnm

ps

kmnm

sm

kmnm

sm

=

=

=

=

+ 10101010

10101010 4

4124

2212

26

00069,025,4290

3

41716125,0

/3

41716125,0

/3

kmnm

ps

kmnm

ps

kmnm

ps

L

cD

B

=

=

= 79,600069,0 10

4

22

Resulting for the optical fiber dispersion coefficient: 2fiber = (7)2 = 49 ps

For 4 km distance: we choose for a transmitter optical rise/fall timetrtr= 90= 90 pspsand for theand for the receiver rise/fall timereceiver rise/fall time recrec = 50= 50 psps

The 3dBThe 3dB--band widthband width forfor recrec is:is: ff3dB = 0,35/3dB = 0,35/recrec = 0,35/50= 0,35/501010--1212 s = 0,007s = 0,007101033101099 = 7 GHz= 7 GHz


13/16



Corp.

13

The operation speedand the band width are characterized by the following relationship:

R = 2R = 2f=1/4f=1/4 22f=1/4f=1/4recrec a = 1/8f = 1/(87109)= (1/56)10-9 ==0,017810-9 s =0,0178 ns = 17,8 ps 2a = (17,8)2(17,8)2 = 316,84ps

Transmitter and receiver impulse response widths are :

tr = (tr /2) = 45 ps 2tr = (45)2 = 2025 psrec = (rec /2) = 25 ps 2rec =(25)2 = 625 ps

The total band width of the impuls (total dispersion of the PCM line):

22 = (= (tr)tr)22 + (+ (rec)rec)22 + (+ (fiber)fiber)22 + (+ (a)a)22 = 2025 ps + 625 ps + 49 ps + 316,84 ps

2

= 3015,84 ps = 54,916 ps (-delta is sometime called the "line dispersion")

The value of the operation speed is:

R =1/4R =1/4 = 1/4 54,916 ps = 1/(454,91610-12)s = 11012/(219,664) s =0,004552 103109 s = 4,54,5 Gb/sGb/s


14/16



Corp.

14

SSWW AVAGOAVAGO PartPart NumberNumbercodingcoding:: AFAFBRBR -- 5757 -- DD7A7A PPZZ

AFAF ==AvagoAvago Fiber OpticsFiber OpticsBRBR = multimode device= multimode device

5757 = SFP (a 59 would be SFF)= SFP (a 59 would be SFF)

DD = 8/4/2G (= 8/4/2G (RR would be 4/2/1G)would be 4/2/1G)

77 = Gen 2 (= Gen 2 (55 = Gen 1)= Gen 1)

AA = extended temp (= extended temp (--10 to 85 C)10 to 85 C)

PP

= bail latch option= bail latch option

ZZ == RoHSRoHS compliantcompliant

LLWW AVAGOAVAGO PartPart NumberNumbercodingcoding:: AFAFCTCT -- 5757 -- DD 5A5ATTPPZZ

AFAF ==AvagoAvago Fiber OpticsFiber Optics

CTCT = single mode device= single mode device

5757 = SFP (a 59 would be SFF)= SFP (a 59 would be SFF)

DD = 8/4/2G (R would be 4/2/1G)= 8/4/2G (R would be 4/2/1G)

55 = Gen 1= Gen 1

AA = extended temp (= extended temp (--10 to 85 C)10 to 85 C)

TT == DFB source for 10DFB source for 10--kmkm ((NN is for 30 km device)is for 30 km device)

PP = bail latch option= bail latch option

ZZ == RoHSRoHS compliantcompliant


15/16



Corp.

15

Observations

The operation speed of the laser optical transceivers deppending hardly from thekey parameters of the photodiode and laserlasertransceivertransceiver..

TheThe keykey parametersparameters areare thethe receiverreceiverandandtransmittertransmitterrise/fallrise/falltimestimes.

R = 1/4R = 1/4 (operation speed)

== [[[[[[[[ ((trtr))22

++ ((recrec))22

+ (+ (fiberfiber))22

+ (+ (aa))22

]]]]]]]]1/21/2

(line dispersion)

trtr

(optical transceiver) Laser transmitter (Laser transmitter (laserdiodelaserdiode))

VCSEL, FPVCSEL, FP--FabryFabry--Perot or DFB lasersPerot or DFB lasers

Rise/Fall time*Rise/Fall time*trtr= 90= 90 psps

mini

GBIC/SFP

Receiver (PIN photodiode)Receiver (PIN photodiode)

Rise/Fall time*Rise/Fall time*recrec = 50= 50 pspsThe tr- rise time of the laser deviceis the time during the output opticalpower of the laser increasing from

10% until 90% ..

10% of opt. power

90% of optical powerpowerpower

riserise

timetimefall timefall time


16/16



Corp.

16

The operation speedcan be different for different optical transceivers which are

characterized by different "key parameters"::::

2 Gb/s

4 Gb/s

8 Gb/s

trtr= 120= 120 psps

recrec = 75= 75 psps

trtr= 90= 90 pspsrecrec = 50= 50 psps

trtr= 60= 60 pspsrecrec = 30= 30 psps

rise/fall time

Remark:::: For SW/300 mwe have < 4 Gb/s

O

P

E

RA

T

I

O

N

SP

E

E

D

sfp op speed

Documents