Transcript small_E - CERN Indico

D. Underwood, Argonne
H. van de Graff, Nikhef
Low Mass Optical Readout for Tracking
The use of optical links could reduce the mass in radiation lengths of the high
bandwidth links to get data off a tracking detector in the SLHC environment.
Examples of two Amplitude Modulators and a Phase Modulator :
A major improvement beyond the conventional form of optical links could be made
by using optical modulators so that the lasers are not in the tracking volume.
Both A M are integrated into CMOS, the P M is compatible with CMOS
Several new technologies which are being investigated primarily for links between
computer chips would allow this with extremely low mass and low power.
Mach-Zender (interferometer) by IBM
AM modulator < 6. 10-5 X0 over a small fraction of the area
Thermal Graded Tipped Fiber Phase Modulator NIKHEF
All these have large bandwidth for device and temperature tolerance
Franz-Keldysh (absorption) by MIT
Investigating hollow fibers and micro lenses and MEMS mirrors with no fibers
MIT Electro-Absorption
IBM
50 u W at 1 Gb/sec
41 mW at 5 Gb/sec
30 u2 footprint
50 u long,
Mach Zender
100 u long x 10 u wide
<6 u thick
Thin, order u
Bandwidth 1539-1553
Broad spectrum 7.3 nm at 1550
Natural operation at 1610-1640 nm, but
strained GeSi to get 1550
80 u long delay line internal, folded
1V p-p AC, 1.6V bias
Example in 180 nm CMOS technology
3 V p-p AC,
Absorption Modulator, using rad-hard fibers.
6 V bias
Same process was used to make a
photodetector
Ultralow Energy, Integrated GeSi ElectroAbsorption Modulators on SOI
Jifeng Liu, Sarah Bernardis, Jing Cheng, Rong Sun, Mark Beals,
Lionel C. Kimerling, and Jurgen Michel
Microphotonics Center, Massachusetts Institute of Technology
Andrew T. Pomerene
BAE Systems, Semiconductor Technology center
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Fabricated with 180 nm CMOS technology
Small footprint (30 µm2)
Extinction ratio: 11 dB @ 1536 nm; 8 dB at 1550 nm
Operation spectrum range 1539-1553 nm (half of the Cband)
• Ultra-low energy consumption (50 fJ/bit, or 50 µW at
1Gb/s)
• GHz bandwidth
Phase Modulator, using rad-hard fibers.
Acknowledgement
EPIC Program, Defense Advanced Research Projects Agency (DARPA).
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Absorption Modulator, using laser beams in gas, in
case radiation damage to fibers is excessive.
Integration of GeSi EAMs into CMOS Process
CMOS
GeSi EAM
Possible use with Back-to-Back layers for
triggering with GEM, Silicon, etc.
2.0 µm
Similar to 3D chips for pixels. Part of
trigger processing is onboard, so not all
the data has to be transported off detector.
GeSi grown between front and backend of CMOS
process for electronic-photonic integration.
Two-step UHVCVD GeSi selective growth:
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(1) a 30-60nm GeSi buffer at 360C; (2) rest of the growth at 600-700C
Annealing at 800-850C decreases dislocation density to ~107/cm2
CMP to remove top facets
M. Beals et al, Proc. SPIE. 6898, 689804 (2008)
GeSi EAMs offers unique benefits for
electronic-photonic integration on Si
• Very small footprint (30 µm2)
• Ultra-low energy consumption (50 fJ/bit)
• >10 dB Extinction ratio
• GHz bandwidth
• Operation spectrum width covering half of the
C-band for on-chip WDM.
REFERENCES
The IBM Mach-Zender:
Single MEMS mirrors similar to this with 2 D
motion can be fabricated on 1 mm cube of Si
through Center for Nanoscale Materials at
Argonne.
Argonne 20 MeV linac accelerator facility
■e- beam energy 8-20
MeV
■Pulse width 30 ps - 5 s
■Pulse to pulse stability
better than 1%
■Repetition rate from
single shot to 60 Hz
■Dose rates to 120 kGy/s
Paper by Green, et al in Optics Express Vol 5, No 25, December
2007
http://www.photonics.com/Content/ReadArticle.aspx?ArticleID=3225
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THE MIT DEVICE:
Paper by Liu, et al. as described in Nature Photonics, December,
2008
http://www.nature.com/nphoton/journal/v2/n7/pdf/nphoton.2008.
111.pdf
http://www.nature.com/nphoton/journal/v2/n7/pdf/nphoton.2008.
99.pdf
Radiation hardness of SiGe electronics:
“Radiation hardness evaluation of SiGe HBT technologies for
the Front-End electronics of the ATLAS Upgrade”, M. Ullána, et
al, NIM A, 579, Sept. 2007, page 828
MEMS mirrors:
“Monolithic MEMS optical switch with amplified out-of-plane
angular motion”,D. Lopez, et al, IEEE Xplore 0-7803-7595-5/02/