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 link

8-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 bond

laser-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 bond

PIN-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 outputsby 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