Radiation-Hard Optical Link for SLHC

K.K. Gan RD07 1

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Radiation-Hard Optical Link for SLHC

June 28, 2007

W. Fernando, K.K. Gan, A. Law, H.P. Kagan, R.D. Kass, S. SmithThe Ohio State University

M.R.M. Lebbai, P.L. SkubicUniversity of Oklahoma

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are needed to see this picture.Outline

Introduction

Bandwidth of micro twisted-pair cables

Bandwidth of fusion spliced SIMM-GRIN fiber

Radiation hardness of PIN/VCSEL arrays

Results on MT-style optical packages based on BeO

Summary

K.K. Gan RD07 3


are needed to see this picture.ATLAS Pixel Opto-Link ArchitectureATLAS is a detector studying pp collisions of 14 TeV at CERN

pixel detector is innermost trackerdetector upgrade planned for Super-LHC in 2015

upgrade based on current pixel link architectureto take advantage of R&D effort and production experience?



micro twisted pairs decouple pixel and opto module production simplify both production

8 m of rad-hard/low-bandwidthSIMM fiber fusion spliced to 70 m rad-tolerant/medium-bandwidthGRIN fiber

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are needed to see this picture.R&D Issues for SLHC

bandwidth of ~ 1 Gb/s is neededcan micro twisted pair transmit at this speed?can fusion spliced SIMM/GRIN fiber transmit at this speed?

can PIN/VCSEL arrays survive SLHC radiation dosage?

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are needed to see this picture.Bandwidth of Micro Twisted Pairs

current pixel cable with thick insulation is quite optimum!

0

500

1000

50 70 90 110 130 150

Length (cm)

Rise Time (20% - 80%) (ps)

80 µm, 7.5 µm Ins, 2 turns/cm127 µm, 9 µm Ins, 2 turns/cm127 µm, 9 µm Ins, 4 turns/cm100 µm, 12.5 µm Ins, 4 turns/cm100 µm, 25 µm Ins, 2 turns/cm100 µm, 25 µm Ins, 4 turns/cm127 µm, 25 µm Ins, 2 turns/cm

(current pixel cable)

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are needed to see this picture.Eye Diagrams100 m current pixel cable

60 cm

transmission at 640 Mb/s is adequatetransmission at 1280 Mb/s may be acceptable127 m cable is slightly better

640 Mb/s

1280 Mb/s

140 cm127 m cable

140 cm

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are needed to see this picture.Bandwidth of Fusion

Spliced Fiber8 + 80 m spliced SIMM/GRIN fiber1 m GRIN fiber

transmission up to 2 Gb/s looks adequate

2 Gb/s

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are needed to see this picture.Radiation Level at SLHC

Optical link of current pixel detector is mounted on patch panel:much reduced radiation level:

Si (PIN) @ SLHC:2.5 x 1015 1-MeV neq/cm2

4.3 x 1015 p/cm2 or 114 Mrad for 24 GeV protonsGaAs (VCSEL) @ SLHC:

14 x 1015 1-MeV neq/cm2

2.7 x 1015 p/cm2 or 71 Mrad for 24 GeV protonsabove estimates include 50% safety margin

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are needed to see this picture.Requirements for PIN/VCSEL

PIN:What is responsivity after irradiation?What is rise/fall time after irradiation?VCSEL:

driver chip most likely be fabricated with 0.13 m process nominal operating voltage is 1.2 V

thick oxide option can operate at 2.5 VVCSELs must need < 2.3 V to produce 10 mA or more

What is rise/fall time after irradiation?What is optical power after irradiation? What current is needed for annealing?

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are needed to see this picture.PIN Responsivity

responsivity decreases by 65% after SLHC dosage

0

2

4

6

8

10

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Pre-irradPost-irrad

Count

Responsivity (A/W)

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OSU V0010 - Advanced Optical Components

0

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2000

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4000

0 2 4 6 8 10 12Current (mA)

Power (µW)

0

0.5

1

1.5

2

2.5

Voltage (V)

OSU V0012 - Optowell

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4000

0 2 4 6 8 10 12

Current (mA)

Power (µW)

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0.5

1

1.5

2

2.5

Voltage (V)

OSU V006 - ULM 10 Gb/s

0

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0 2 4 6 8 10 12Current (mA)

Power

(µW)

0

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Voltage (V)

OSU V005 - ULM 5 Gb/s

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4000

0 2 4 6 8 10 12Current (mA)

Power (µW)

0

0.5

1

1.5

2

2.5

Voltage (V)

VCSEL LIV Characteristics

ULM requires higher voltage to operateall arrays have very good optical power

Optowell AOC

ULM 10GULM 5G

Pre-irrad

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Optowell

71 MRad

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0 100 200 300 400

Time (Hours)

Data Optical Power (mW)

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20

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60

80

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120

Dose (Mrads)

Ch 1

Ch 2

Ch 3

Ch 4

Ch 5

Ch 6

Ch 7

Dose

VCSEL Power vs Dosage

Optowell survives to SLHC dosagemore VCSELs might survive with more annealing during irradiation

SLHC

AOC

71 MRad

0.0

0.3

0.6

0.9

1.2

1.5

1.8

0 100 200 300 400

Time (Hours)


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Dose (Mrads)

Ch 1

Ch 2

Ch 3

Ch 4

Ch 5

Ch 6

Ch 7

Dose

AOC

ULM 5G

71 MRad

0.0

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0.8

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1.6

2.0

2.4

2.8

0 100 200 300 400

Time (Hours)


0

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120

Dose (Mrads)

Ch 1

Ch 2

Ch 3

Ch 4

Ch 5

Ch 6

Ch 7

Dose

ULM 10G

71 MRad

0.0

0.3

0.6

0.9

1.2

1.5

0 100 200 300 400

Time (Hours)


0

20

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120

Dose (Mrads)

Ch 1

Ch 2

Ch 3

Ch 4

Ch 5

Ch 6

Ch 7

Dose

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are needed to see this picture.Opto-Pack Development

current pixel detector uses Taiwan optical packagesVCSEL mounted on PCB with poor heat conductionmicro soldering of 250 m leads is difficult

Ohio State develops new opto-pack for SLHCuses BeO base with 3D traces for efficient heat removalwire bond to driver/receiver chip



OSU

Taiwan

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Results on Opto-Packs30 VCSEL/PIN opto-packs have been fabricatedall VCSEL opto-packs have good coupled powerprinciple of new opto-pack has been demonstrated

0

1000

2000

3000

1 3 5 7 9 11

Channel

Power (_)W

012V Optowell 013V Optowell

002V AOC 010V AOC

004 5 /V ULM Gb s 005 5 /V ULM Gb s

006 10 /V ULM Gb s 007 10 /V ULM Gb s

MT ferrule

Ceramic guide pin

VCSEL array

1 cm

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Summarymicro twisted-pair cable of current ATLAS pixel detectorcan be usedfor transmission up to 1 Gb/sfusion spliced SIMM/GRIN fiber can transmit up to 2 Gb/sPIN responsivity decreases by 65% after SLHC dosageOptowell VCSEL survives SLHC dosagecurrent opto-link architecture satisfies SLHC requirementscompact MT-style opto-pack based on BeO has been developed

Radiation-Hard Optical Link for SLHC

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