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Radiation-Hard Optical Link for SLHC. W. Fernando, K.K. Gan, A. Law, H.P. Kagan, R.D. Kass, S. Smith The Ohio State University. M.R.M. Lebbai, P.L. Skubic University of Oklahoma. June 28, 2007. Outline. l Introduction l Bandwidth of micro twisted-pair cables
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Radiation-Hard Optical Link for SLHC W. Fernando, K.K. Gan, A. Law, H.P. Kagan, R.D. Kass, S. Smith The Ohio State University M.R.M. Lebbai, P.L. Skubic University of Oklahoma June 28, 2007 RD07
Outline lIntroduction lBandwidth of micro twisted-pair cables lBandwidth of fusion spliced SIMM-GRIN fiber lRadiation hardness of PIN/VCSEL arrays lResults on MT-style optical packages based on BeO lSummary RD07
ATLAS Pixel Opto-Link Architecture lATLAS is a detector studying pp collisions of 14 TeV at CERN upixel detector is innermost tracker udetector upgrade planned for Super-LHC in 2015 a upgrade based on current pixel link architecture to take advantage of R&D effort and production experience? micro twisted pairs decouple pixel and opto module production a simplify both production 8 m of rad-hard/low-bandwidth SIMM fiber fusion spliced to 70 m rad-tolerant/medium-bandwidth GRIN fiber RD07
R&D Issues for SLHC lbandwidth of ~ 1 Gb/s is needed ucan micro twisted pair transmit at this speed? ucan fusion spliced SIMM/GRIN fiber transmit at this speed? lcan PIN/VCSEL arrays survive SLHC radiation dosage? RD07
Bandwidth of Micro Twisted Pairs (current pixel cable) lcurrent pixel cable with thick insulation is quite optimum! RD07
Eye Diagrams 127 m cable 100 m current pixel cable 140 cm 140 cm 60 cm 640 Mb/s 1280 Mb/s ltransmission at 640 Mb/s is adequate ltransmission at 1280 Mb/s may be acceptable l127 m cable is slightly better RD07
Bandwidth of Fusion Spliced Fiber 8 + 80 m spliced SIMM/GRIN fiber 1 m GRIN fiber 2 Gb/s ltransmission up to 2 Gb/s looks adequate RD07
Radiation Level at SLHC lOptical link of current pixel detector is mounted on patch panel: amuch reduced radiation level: uSi (PIN) @ SLHC: n2.5 x 1015 1-MeV neq/cm2 n4.3 x 1015 p/cm2 or 114 Mrad for 24 GeV protons uGaAs (VCSEL) @ SLHC: n14 x 1015 1-MeV neq/cm2 n2.7 x 1015 p/cm2 or 71 Mrad for 24 GeV protons uabove estimates include 50% safety margin RD07
Requirements for PIN/VCSEL lPIN: u What is responsivity after irradiation? uWhat is rise/fall time after irradiation? lVCSEL: udriver chip most likely be fabricated with 0.13 mm process nnominal operating voltage is 1.2 V nthick oxide option can operate at 2.5 V aVCSELs must need < 2.3 V to produce 10 mA or more uWhat is rise/fall time after irradiation? uWhat is optical power after irradiation? uWhat current is needed for annealing? RD07
PIN Responsivity lresponsivity decreases by 65% after SLHC dosage RD07
VCSEL LIV Characteristics Optowell AOC Pre-irrad ULM 10G ULM 5G 6ULM requires higher voltage to operate lall arrays have very good optical power RD07
VCSEL Power vs Dosage SLHC lOptowell survives to SLHC dosage lmore VCSELs might survive with more annealing during irradiation RD07
Opto-Pack Development lcurrent pixel detector uses Taiwan optical packages nVCSEL mounted on PCB with poor heat conduction nmicro soldering of 250 mm leads is difficult lOhio State develops new opto-pack for SLHC nuses BeO base with 3D traces for efficient heat removal nwire bond to driver/receiver chip OSU Taiwan RD07
Results on Opto-Packs l30 VCSEL/PIN opto-packs have been fabricated uall VCSEL opto-packs have good coupled power aprinciple of new opto-pack has been demonstrated 1 cm MT ferrule VCSEL array Ceramic guide pin RD07
Summary lmicro twisted-pair cable of current ATLAS pixel detector can be usedfor transmission up to 1 Gb/s lfusion spliced SIMM/GRIN fiber can transmit up to 2 Gb/s lPIN responsivity decreases by 65% after SLHC dosage lOptowell VCSEL survives SLHC dosage acurrent opto-link architecture satisfies SLHC requirements lcompact MT-style opto-pack based on BeO has been developed RD07