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Experience with Parallel Optical Link for the CDF Silicon Detector

Experience with Parallel Optical Link for the CDF Silicon Detector. S. Hou for the DOIM group Academia Sinica, Taiwan. Introduction. DOIM: D ense Optical Interface Module Byte-wide parallel optical link 8-bits + clock 53 Mbyte/sec, BER  10 -12 Transmitter : Laser-diode array

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Experience with Parallel Optical Link for the CDF Silicon Detector

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

  2. Introduction • DOIM: Dense Optical Interface Module • Byte-wide parallel optical link • 8-bits + clock • 53 Mbyte/sec, BER10-12 • 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

  3. 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 mW/ch @20mA • Insertion to fiber: • 200 ~ 800 W/ch • Fabrication by • Chunghwa Telecom • Telecommunication Laboratories VERTEX 2002

  4. 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 : • Vcc-VLD across • output transistor, 50 , laser • control current consumption • At 3V, 20mA/ch nominal • ~2mA/0.1V adjustable slope VERTEX 2002

  5. 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

  6. 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

  7. Receiver assembly • Die-bond / Wire bond • PIN-diode array on Al2O3 submount • driver chip on substrate • fibers on V-groove • Alignment, fibers to PIN-diodes VERTEX 2002

  8. Assembly procedure VERTEX 2002

  9. 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

  10. Laser diode: L-I-V • Laser light at 20, 30, 40oC • water-bath chiller precision ~0.1oC • 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

  11. 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

  12. 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

  13. Transmitter uniformity : light outputs • Production transmitters • light from pigtail at 30oC • 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

  14. 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

  15. 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, (2nd batch) • =0.7% • 4% wider in 1st batch • due to chip tuning • Wide light input range • Saturation monitored at 970 W VERTEX 2002

  16. 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

  17. 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

  18. Accelerated Aging test • 4 transmitters at 60oC, 330 days • Wear-out degradation • 0.15 0.08 W/day at 60oC • no failure • Accelerating factor • F=exp(Ea/kb) (1/T1 –1/T2) • F=29 for T= – 5oC • Failure due to light degradation • Min transmitter spec 200 W • down 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

  19. 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

  20. 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

  21. 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

  22. DOIM implementation : transmitters • Transmitters on Port Cards • Total 570 transmitters • 128 Port Cards, • 5 transmitter each board VERTEX 2002

  23. DOIM implementation : receivers • Receivers on FTM • 10 receivers on each board, reading 2 Port Cards VERTEX 2002

  24. Status • 570 pairs implemented • ~10 % bit-error flagged • excess light at -5oC • optical reflection, contact • electrical pin contact • 2% has fatal damage • is improving VERTEX 2002

  25. 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 VERTEX 2002

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