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

VERTEX 2002 Introduction DOIM: D ense Optical Interface Module Byte-wide parallel optical link 8-bits + clock 53 Mbyte/sec, BER  Transmitter : Laser-diode array ASIC driver chip Receiver : PIN-diode array ASIC 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 wavelength 12-ch diode array (9 used) 250  m pitch 20 mA/channel Cleaved mirrors Facet coating Bare laser power:  1 Insertion to fiber: 200 ~ 800  W/ch Fabrication by Chunghwa Telecom Telecommunication Laboratories

VERTEX 2002 Transmitter: driver ASIC Custom design, biCMOS 0.8  m,AMS bipolar transistors only Inputs : Diff. ECL or LVDS signals compatible differential  100 mV Enable by TTL low Nine channels : V cc -V LD 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 submount driver chip on substrate fibers on V-groove Alignment fibers to laser emitting facets

VERTEX 2002 Receiver : PIN & ASIC InGaAs/InP PIN diode : 12-ch array, matching laser diode wavelength by TL, Chunghwa Telecom. Operation condition : 50 ~ 800  W on,  10  W off  1.1 W/module Outputs : differential ECL, nine independent channels

VERTEX 2002 Receiver assembly Die-bond / Wire bond PIN-diode array on Al 2 O 3 submount driver chip on substrate fibers 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% +Dcyc Laser light MT-12ST fanout & Tek O/E probe

VERTEX 2002 Laser diode: L-I-V Laser light at 20, 30, 40 o C water-bath chiller precision ~0.1 o C measured at substrate I-V little temperature dependence approximately linear L-V Drop with temperature Duty cycle diff. 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 ~0.1 o C Approximately linear drop to temperature

VERTEX 2002 Receiver response Receiver connected to a Transmitter Light power chosen for wide 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 transmitters light from pigtail at 30 o C wide deviation channel-by-channel mainly 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 deviation Is approximately a const. scaling factor L-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 batches monitored at 550  W & 970  W light pulse width 45% ECL duty cycle is uniform 48.1% at 550  W, (2 nd batch)  =0.7% 4% wider in 1 st 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 Fermilab PC ISA boards TTL to Tbert, 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 60 o C, 330 days Wear-out degradation 0.15  0.08  W/day at 60 o C no failure Accelerating factor F=exp( E a / k b ) (1/T 1 –1/T 2 ) F=29 for T= – 5 o C Failure due to light degradation Min transmitter spec 200  W down below receiver threshold 50  W ~100 days at 60 o C, or 8 years at – 5 o C 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 flagged excess light at -5 o C optical reflection, contact electrical pin contact  2% 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