VERTEX 2002 Experience with Parallel Optical Link for the CDF Silicon Detector S. Hou for the DOIM group Academia Sinica, Taiwan.

VERTEX 2002

Experience with Parallel Optical Linkfor the CDF Silicon Detector

S. Hou for the DOIM groupAcademia Sinica, Taiwan

VERTEX 2002

Introduction

DOIM: Dense Optical Interface Module

Byte-wide parallel optical link8-bits + clock53 Mbyte/sec, BER10-12

Transmitter :Laser-diode arrayASIC driver chip

Receiver :PIN-diode arrayASIC receiver chip

Multi-mode fiber ribbon

Laser, Electrical characteristics

Bit-error rate test

Aging test

Radiation Hardness

Implementation in CDF

VERTEX 2002

Transmitter: Laser diode

InGaAs/InP Edge-emitting laser diode :1550 nm wavelength12-ch diode array (9 used)250 m pitch20 mA/channel

Cleaved mirrorsFacet coating

Bare laser power: 1 mW/ch @20mAInsertion to fiber: 200 ~ 800 W/ch

Fabrication byChunghwa Telecom Telecommunication Laboratories

VERTEX 2002

Transmitter: driver ASIC

Custom design, biCMOS 0.8 m,AMSbipolar transistors only

Inputs :Diff. ECL or LVDS signals compatibledifferential 100 mVEnable by TTL low

Nine channels :Vcc-VLD across output transistor, 50 , laser control current consumption

At 3V, 20mA/ch nominal ~2mA/0.1V adjustable slope

VERTEX 2002

Transmitter assembly

Die-bond / Wire bondlaser-diode array on BeO submountdriver chip on substratefibers on V-groove

Alignmentfibers to laser emitting facets

VERTEX 2002

Receiver : PIN & ASIC

InGaAs/InP PIN diode :12-ch array, matching laser diode wavelengthby TL, Chunghwa Telecom.

Operation condition :50 ~ 800 W on, 10 W off1.1 W/module

Outputs :differential ECL, nine independent channels

VERTEX 2002

Receiver assembly

Die-bond / Wire bondPIN-diode array on Al2O3 submountdriver chip on substratefibers on V-groove

Alignment, fibers to PIN-diodes

VERTEX 2002

Assembly procedure

VERTEX 2002

Transmitter characteristics

Transmitter tests :L-I-V and temperature 50 MHz diff. Inputs, 2.5V common mode 100 mV, 50% +DcycLaser light MT-12ST fanout & Tek O/E probe

VERTEX 2002

Laser diode: L-I-V

Laser light at 20, 30, 40oCwater-bath chiller precision ~0.1oCmeasured at substrate

I-V little temperature dependenceapproximately linear

L-V Drop with temperature

Duty cyclediff. Input 50%stable, little offset to 50%

VERTEX 2002

Laser diode: temperature

Light power vs. Temperature

Measured in stable cooling/heating process

Temperature at substrate precision ~0.1oC

Approximately linear drop to temperature

VERTEX 2002

Receiver response

Receiver connected to a Transmitter

Light power chosen forwide distribution

Light pulse width are consistent

Receiver ECL outputs

by a Tektronix diff. probe

Consistent duty cycles in favored operation range (2.8~3.2V)

Saturates for high light level

VERTEX 2002

Transmitter uniformity : light outputs

Production transmitterslight from pigtail at 30oCwide deviation channel-by-channelmainly due to insertion efficiency

Span within ~400 W ~72 W to the mean/module

Effect operation dynamic range in threshold, saturation limit

VERTEX 2002

Transmitter uniformity : light pulse widths

Ch-Ch Light power deviationIs approximately a const. scaling factorL-V linear fit, normalized slope to L(3V) indep. of light power

Light pulse width is uniform, ~1%, indep. of light power

VERTEX 2002

Receiver uniformity : ECL duty cycles

Two production batchesmonitored at 550 W & 970 Wlight pulse width 45%

ECL duty cycle is uniform48.1% at 550 W, (2nd batch)=0.7%

4% wider in 1st batch

due to chip tuning

Wide light input range Saturation monitored at 970 W

VERTEX 2002

Receiver uniformity : duty cycle deviation

Input lights~950 W, width 45%

for all channels

ECL outputs of a module

deviation to the mean ~1.5%

for both batches

VERTEX 2002

Bit-Error Rate test

BERT by FermilabPC ISA boards TTL toTbert, Rbert boards

At 63 MHz, minimum BER 10 –12

Burn-in 3-days on ASICs, diodes 1-day BERT

reject devices infant mortality

bad components fail quickly

VERTEX 2002

Accelerated Aging test

4 transmitters at 60oC, 330 days

Wear-out degradation0.15 0.08 W/day at 60oCno failure

Accelerating factor

F=exp(Ea/ kb) (1/T1 –1/T2)

F=29 for T= – 5oC

Failure due to light degradationMin transmitter spec 200 Wdown below receiver threshold 50 W~100 days at 60oC, or 8 years at – 5oC

90% C.L. for 0 failure, P=0.064 upper limit = 40 ch. In 3 years

VERTEX 2002

INER 30 MeV proton Irradiation

CDF requirement : 200 kRad tolerance

INER test beam : transmitter in DC mode.

fiber connection out of beam area, measuring L, T versus dose.

VERTEX 2002

Bulk damage, annealing

Bulk damage dominant, linear dep. to dose

Ratio of light drop is consistent for a module, indep. of light power

Degradation 10% for 200 kRad

VERTEX 2002

UC Davis 63.3 MeV proton

UC Davis test beam : 10 transmitters on two Port Cards

Examined after 200, 400 kRad, for L I, V measurements

Light degradation ~10% for 200 kRad

Similar I-V, L-V characteristics after irradiation,

slope for L vs. V degrades similarly.

VERTEX 2002

DOIM implementation : transmitters

Transmitters on Port Cards

Total 570 transmitters

128 Port Cards,

5 transmitter each board

VERTEX 2002

DOIM implementation : receivers

Receivers on FTM

10 receivers on each board, reading 2 Port Cards

VERTEX 2002

Status

570 pairs implemented

~10 % bit-error flaggedexcess light at -5oCoptical reflection, contactelectrical pin contact2% has fatal damage

is improving

VERTEX 2002

Summary

DOIM, a byte-wide optical link is implemented in CDF

Edge-emitting laser light linear to I-V and T

Laser-diode array coupling to pigtail fibers large deviation a major disadvantage

Radiation tolerance is high bulk-damage dominant linear degradation to dose