optical interface for 100g smf 10km...

Optical Interface for 100G SMF 10km PMD

Matt TraversoMasato Shishikura

Kiyo Hiramoto

IEEE Interim Seoul, KoreaSeptember 2007

2

Supporters

• Masahiro Aoki, Hitachi Ltd.• Frank Chang, Vitesse• John Dallesasse, Emcore• Ali Ghiasi, Broadcom• Shinji Nishimura, Hitachi Ltd.• Hidehiro Toyoda, Hitachi Ltd.

3

Agenda

• Next Steps to standardize SMF “short” reach PMD• Wavelength Spacing; CWDM vs. Narrow Spacing

(iWDM)• Wavelength Grid Impact on Chromatic Dispersion

Penalty– Modulation: EA type versus DM type– Reach Considerations

4

Path to Move Forward

• Key Milestones for PMD Standardization– Approximate Distance and Media included in the PAR

• “Provide Physical Layer specifications which support 100 Gb/soperation over: … at least 10km on SMF”

– Outline in Brief• Select Lane width of optical interface• Select Wavelength(s) and Approximate Grid• Propose Optical Budget• Refine Distance Target & other parameters• Iterate Analysis and Refinements of PMD

5

Reiterate Case for 4x25Gbit/s

• Lane rate of ~25Gbit/s scales well for future generations of IC technology

• From optics point of view simpler interconnect and packaging than 40Gbit/s– Intention is to leverage 10Gbit/s packaging and interconnect

technology

• Modulation of 25Gbit/s suitable for a direct modulation laser– Implementation of 25Gbit/s DML depends upon the final distance

objective

6

CWDM vs. Narrow Spacing (iWDM)

• CWDM allows for use of uncooled lasers• iWDM requires use of a thermoelectric cooler (TEC) to maintain the

laser chip(s) at constant temperature– Likely that 4 individual TECs would be required for initial implementation

• CWDM spacing therefore will yield modules with lower power dissipation

CWDM Proposal for 10km PMD

Proposal for 40km PMD

2.2 nm Pitch

1nm Bandwidth

80 nm1361 nm1291 nm

63 nm1294.5 nm 1357.5 nm

8.8 nm

7.6 nmSimilar to iWDM proposal

7

Power & Cost comparison; CWDM vs. iWDM

• CWDM module can achieve: – Lower cost than tighter wavelength spaced module– Considers the cost of the laser relative to the wavelength spread of the wafer

• Initially CWDM module will likely be similar in power consumption via wide-temperature semi-cooled EA-DFB

• In the future, as uncooled technology matures:– CWDM module can achieve ~ 2 W lower power consumption – Lower cost due to larger proportion of die in the acceptable wavelength region

LD typePower

consumption(W)

Realtive Cost(Wavelength

tolerance)LD type

Powerconsumption

(W)

Realtive Cost(Wavelength

tolerance)

1310nm CWDM CooledEA-DFB 6 1.0

(+/-6nm)Uncooled

DFB 1.60.8 to 1

(+/-1.1 to 2.6nm)

1310nm iWDM CooledEA-DFB 6 2.8

(+/-0.35nm)Cooled

DFB 3.3 2.8(+/-0.35nm)

First Generation Future

8

CWDM(ITU-T) grid study for 10 km

Objective- Which CWDM(ITU) grid set is better, 1271-1331nm or 1291-1351nm ?- How much is chromatic dispersion penalty ?

Simulate the penalty of each CWDM grid setHypothesis- Bit rate: 25.8Gbps- Distance: 10 km- Without non-linear effect - TX tr/tf: 15ps(20-80%)- Waveform: Super-Gaussian (*1)

Parameter- α: -1~4 (EA:-1~1, DM:2~7) (*2)- Extinction ratio: 5~10dB

B2B, ER=7dB, λ0=1312nm, tr/tf=15ps

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)

B2B optical waveform

Note(*1): Does not simulate actual waveforms of EML and DM DFB-LD.Note(*2): alpha is set constant.

9

Chromatic dispersion

Dispersion@10km,SSMF- 1271-1331nm: -59ps/nm(min), 33ps/nm(max), |DZ|=59ps/nm(max) - 1291-1351nm: -38ps/nm(min), 50ps/nm(max), |DZ|=50ps/nm(max)

Chromatic Dispersion

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

8

1251 1261 1271 1281 1291 1301 1311 1321 1331 1341 1351 1361 1371

Wavelength (nm)

Chro

mat

ic D

ispe

rsio

n (

ps/nm

/km

)

λ0(nm) min 1300 λ0(nm) center 1312 λ0(nm) max 1324

1271 1291 1311 1331 1351

1300

1312

1324

λ0=

-5 .94ps/nm/km

-3 .85ps/nm/km

5 .02ps/nm/km

3 .34ps/nm/km

Chromatic Dispersion 10km

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

60

70

80

1251 1261 1271 1281 1291 1301 1311 1321 1331 1341 1351 1361 1371

Wavelength (nm)

Chro

mat

ic D

ispe

rsio

n@

10km

(ps

/nm

)

λ0(nm) min 1300 λ0(nm) center 1312 λ0(nm) max 1324

1271 1291 1311 1331 1351

1300

1312

1324

λ0=

-59 .36ps/nm

-38 .46ps/nm

50 .17ps/nm

33 .44ps/nm

10

EA-Mod: 10km CD Penalty

CWDM grid set (EA: -1<α<1)- 1291-1351nm grid set is better- CD penalty@10km: ~1dB

EA 10km（-1<α<1、Er=7dB）

-1

-0.5

0

0.5

1

1.5

2

1251 1271 1291 1311 1331 1351 1371

Wavelength (nm)

CD

penal

ty @

10km

(dB

)

α=-1（λ0=1324nm) α=1（λ0=1300nm)

1271 1291 1311 1331 1351

1.24dB

0.99dB

B2B, ER=7dB, λ0=1312nm, tr/tf=15ps

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)

α=-1, λ=1264.5ｎｍ, 10km, ER=7dB, λ0=1324nm,tr/tf=15ps

0

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1.2

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Time (ps)

Am

plit

ude

(ar

b. u

nit

)

α=1, λ=1337.5ｎｍ, 10km, ER=7dB, λ0=1300nm,tr/tf=15ps

0

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1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)

B2B

λ=1264.5nmpenalty=1.24dBα=-1λ0=1324nm

λ=1357.5nmpenalty=0.99dBα=1λ0=1300nm

0.25dB

α=1, λ0=1300nmα=-1, λ0=1324nm

11

Direct Mod: 10km CD Penalty

CWDM grid set (DM: 2<α<4)- 1271-1331nm set is better- But penalty >>2dB - New lower chirping technologyis needed (α<2)

CD penalty @ 10km

0

1

2

3

4

5

6

7

8

9

10

-2 -1 0 1 2 3 4 5

alpha

CD

penal

ty @

10km

(dB

)

1271-1331 1291-1351

EA-DFB DM-DFB


0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)


0

0.2

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1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)


0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)

λ=1357.5nm(λ0=1300nm)

α=2

λ=1337.5nm(λ0=1300nm)

penalty=3.52dB

penalty=2.24dB

penalty=1.32dB


0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)

penalty=2.33dB


0

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1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)

penalty=4.50dB


0

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0.6

0.8

1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)

penalty=9.52dB

α=3

α=4

12


CD penalty @ 2km (DM)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 2 3 4 5

alpha

CD

penal

ty @

10km

(dB

)

1271-1331 1291-1351

DM: α>2

CWDM grid set - CD penalty is less than 1dB

each grid set (DM: 2<α<4)

λ=1357.5nm(λ0=1300nm)

α=2

λ=1337.5nm(λ0=1300nm)

α=3

α=4


0

0.2

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1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)


0

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Am

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Time (ps)

Am

plit

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0

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0 20 40 60 80

Time (ps)

Am

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b. u

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0

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Time (ps)

Am

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b. u

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0

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Time (ps)

Am

plit

ude

(ar

b. u

nit

)

penalty=0.43dBpenalty=0.68dB



13


λ=1357.5nm(λ0=1300nm)

λ=1337.5nm(λ0=1300nm)

α=1α=1, λ=1357.5ｎｍ, 4km, ER=6dB, λ0=1300nm,

tr/tf=15ps

0

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0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

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Am

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(ar

b. u

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Am

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(ar

b. u

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α=2 α=3 α=4 α=5 α=6


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b. u

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b. u

nit

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Am

plit

ude

(ar

b. u

nit

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0

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Time (ps)

Am

plit

ude

(ar

b. u

nit

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0

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0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)


0

0.2

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0.6

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Time (ps)

Am

plit

ude

(ar

b. u

nit

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α=1 α=2 α=3 α=4 α=5 α=6

Dispesion penalty @4km (DM)

0

0.5

1

1.5

2

2.5

3

3.5

0 2 4 6 8

alpha

Dispe

rsion penalty (dB

)

1271-1331 1291-1351

Pd=0.33dB Pd=0.7dB Pd=1.12dB Pd=1.6dB Pd=2.18dB Pd=2.87dB

Pd=0.21dB Pd=0.44dB Pd=0.69dB Pd=0.96dB Pd=1.26dB Pd=1.59dB

B2B, ER=6dB, tr/tf=15ps

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80

Time (ps)

Am

plit

ude

(ar

b. u

nit

)

BtoB

14

Summary Wavelength Grid

Optimum Wavelength Grid depends upon distance objective10km: 1291-1351nm- Dispersion penalty of ~1dB

• Better by 0.25dB than 1271-1331nm set. • With α of EA from -1 to 1 (*NOTE 1)

4km: 1271-1331nm- Dispersion penalty of ~1dB (*NOTE 2)

• Better by 0.6dB than 1291-1351nm set. • With α of DM as 4

2km: 1271-1331nm- Dispersion penalty of ~0.5dB

• Better by 0.2dB than 1291-1351nm set. • With α of DM as 4

*NOTE 1: New DM technology required to achieve 10km application due to large α of current DM technology; (α<2 is needed) *NOTE 2: Fixed α was used, therefore the simulation may be optimistic relative to real DML & EA-DFB devices.

optical interface for 100g smf 10km...

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