Anl Optical

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  • 1. Updates on Optical ProjectsJune, 2011 B. Fernando,P.M. DeLurgio,R. Stanek,B. Salvachua,D. UnderwoodANL-HEP D. LopezANL Center for Nanoscale Materials August 22, 2011

2. Motivation

  • Develop and adapt new technologies to improve optical communication in HEP experiments
    • Increase speed, reduce the mass of the system, Increase reliability
  • Test operation of new devices with the environmental conditions of
    • Radiation hardness, low temperature operation, Reliability
  • Introduce the technologies to real detectors
  • Investigate techniques to eliminate fibers, cables and connectors

August 22, 2011 3. Issues with Current HEP Optical Links

  • Most LHC optical link failures are due to VCSEL failures and brokensolder joints
    • More spare links (?)
  • VCSELs need
    • High current driver chips (radiation hard) which need a lot of power and control wires
    • Power cables (to supply current)
    • Need to tune links individually(need control wires)
    • Cooling/Heating
  • ESD/moisture sensitivity
    • Issue with custom packaging (non industry)
  • High current density
  • Radiation tolerance
    • Commercial VCSEL's have only limited radiation tolerance, which is probably not adequate

Increase Amount of material insidedetector Reliability issues 4. Proposed Optical Scheme(ideal) August 22, 2011

    • High bandwidth :
      • no chirp commercial systems work >10 Gb/s/channel
    • Low material budget:
      • Less total power inside detectorless cooling needed (stainless steel/copper)
      • Fewer control wires
    • Higher reliability :
      • Laser sources outside the detector,
      • Dont need separate high current drivers, less radiation/ESD/humidity sensitivity
    • Smaller in size
      • Modulators/PIN diodes can be integrated into a single die

n n Power On detector (n=12?) Outside (counting room) Fibers /free spacelinks CW laser Fibers Single chip Modulator*n PIN diode*n Data, TTC TIA AMP Single chip(possibility in future) Modulator*n PIN diode*n TIA*n AMP*n Control Chip/sensors 5. Detector Applications: Requirements

  • Calorimeters (Tile, Liquid Argon):
    • Highly serialized data fast (8-10 Gb/s links)
    • Less radiation ( ~10 13Protons/cm 2)
    • Standard interface with industry standards (snap 12?)
    • Reliability is an issue because there can be no access for years
  • Tracker(pixel detector, silicon tracker)
    • More data fast (atlas pixel: 5Gb/s out)
    • High radiation (~10 15Protons/cm 2)
    • Low temperature operation (~-20 C )
    • Reliable (no access after the detector closed)
    • Low power consumption (VCSEL based ~40mW/channel)
    • Less mass (material inside)
    • Custom interface (LVDS input)


  • Technologies

August 22, 2011 7. on off a-Si GeSi a-Si a-Si GeSi a-Si Tapered vertical coupler MIT Design of GeSi EAM Device Structure Liu et al, Opt. Express. 15, 623-628(2007) MIT Modulators

  • Fabricated with 180 nm CMOS technology
  • Small footprint (30 m2)
  • Extinction ratio: 11 dB @ 1536 nm; 8 dB at 1550 nm
  • Operation spectrum range 1539-1553 nm (half of the C-band)
  • Ultra-low energy consumption (50 fJ/bit, or 50 W at 1Gb/s)
  • GHz bandwidth
  • 3V p-p AC, 6 V bias
  • Same process used to make a photodetector

8. 41 mW at 5 Gb/sec 100 u longx 10 u wide Thin,order u Broad spectrum7.3 nm at 1550 80 u long delay lineinternal 1V p-pAC, 1.6V bias IBM Modulators 9. Advances are Needed in Procuring Modulators

  • ANL Bench tests use LiNO3 modulators fast, rad hard, but not small
  • MIT and IBM have prototypes of modulators to be made inside CMOS chips
    • It would cost us severalx $100k for 2 foundry runs to make these for ourselves
    • Currently both designs are not being actively pursued
  • We may have found a vendor (Jenoptik) for small modulators who will work with us on ones which can be wire-bonded and have single-mode fiber connections
    • Need to test for radiation hardness of these
  • There are commercial transceiver of small size such as LUX5010A ( )
    • Fit most of the requirements, need to find out radiation hardness and low temperature operation

10. Collaboration with industry

  • Testing radiation hardness of commercial modulators
  • Design and construct a radiation-hard silicon modulator chip
  • Building a transceiver
  • Communication within different layers to improve the trigger efficiency

August 22, 2011 11. The Luxtera/Molex Commercial Devices Good Unknown Fast (4x 10G) Radiation hardness Design is very close to our ideal design Low temperature operation Fibers are pure glass, no plastic insideNo need of connectors, drivers pin diodes, etc. Very small 12. The Luxtera/Molex design [ link ] 13. Testing Plan for (Jenoptik/Molex)

  • Test the operation at -20C
  • Few Total Ionizing Dose (TID) testing rounds at ANL with electrons
    • Test unmodified devices first.
    • Can give some feedback and If request for modifications to standard device is accepted these also to be tested
    • Test using 200 MeV protons up to 10 15Protons/cm 2
    • Couple of batches (improve/unmodified..etc)

14. FUTURE 15. Future Directions

      • Test radiation hardness and low temperature operation of Commercial modulatorsand improve it for HEP optical links
      • Build HEP modulators if funding obtained (collaboration with industry )
      • More robust long distance optical link
      • Local triggering using optical communication between tracking layers

Some concepts for interlayer communication for input to trigger decisions 16. Backup August 22, 2011 17. Optical links failures at LHC

  • VCSEL failures in ATLAS before beam
  • VCSEL failuresmeeting
  • ACES meeting on optical links few failures in CMS
  • TWEPP 2010 CMS operations"We continue to have failures of the optical links" (off detector)
  • LHCB VCSEL failures
  • CERN Twiki on VCSEL failures (TT and IT )


  • Technologies

August 22, 2011 19. Technology : Free-Space Communication to replace fibers and cables

  • Advantages:
    • Low Mass
    • No fiber routing
    • Low latency (No velocity factor)
    • Low delay drift (No thermal effects such as in fibers)
    • Work over distances from few mm (internal triggers) to ~Km (counting house) or far ( to satellite orbit)
    • Communicate between ID layers for trigger decisions.

20. Main Parts of Project

  • Design of lens systemsto send and receive modulated laser lightthrough free space.
  • Incorporate modulatorsto modulate the laser beam
  • UseMEMS mirrorto guide the beam to the receiver and the use of afeedback mechanismto keep the beam locked to the receiver.
  • Setup for bit error rate testing
  • Demonstrate practical application, e.g. ANL DHCAL at Fermilab (this application not yet funded)

August 22, 2011 21.

  • The commercial MEMS mirrors have ~40 dB resonance peaks at 1 and 3 KHz.
  • To us