Optical Switch Fabrics: What is their value, and When will they deliver it?

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Optical MEMSOverview MARS Modulator
Joseph Ford, James Walker, Keith Goossen
References Silicon modulator based on
mechanically-active antireflection layer with 1
Mbit/sec capability K. Goossen, J. Walker
and S. Arney, IEEE Photonics Tech. Lett. 6,
p.1119, 1994 "Micromechanical fiber-optic
attenuator with 3 microsecond response"   J.
Ford, J. Walker, D. Greywall and K. Goossen, IEEE
J.of Lightwave Tech. 16(9), 1663-1670, September
1998  "Dynamic spectral power equalization using
micro-opto-mechanics"   J. Ford and J.
Walker, IEEE Photonics Technology Letters
10(10), 1440-1442, October 1998 
"Micromechanical gain slope compensator for
spectrally linear power equalization"   K.
Goossen, J. Walker, D. Neilson, J. Ford, W. Knox,
 IEEE Photonics Tech. Lett.12(7), pp. 831-833,
July 2000.  "Wavelength add/drop switching using
tilting micromirrors"   J. Ford, V. Aksyuk,
D. Bishop and J. Walker, IEEE J. of Lightwave
Tech. 17(5), 904-911, May 1999.  "A tunable
dispersion compensating MEMS all-pass filter"   
Madsen, Walker, Ford. Goossen, Nielson,
Lenz, IEEE Photonics Tech. Lett. 12(6), pp.
651-653, June 2000.
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What are MEMS? Micro-Electro-Mechanical Systems

• Surface Micromachining
• LIGA (electroforming)
• Deep Reactive Ion Etching

• Electrostatic attraction
• Electromagnetic force
• Electrostriction
• Resistive heating

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Mass commercial application Acceleration Sensors
Analog Devices' ADXL50 accelerometer Surface
micromachining capacitive sensor 2.5 x 2.5 mm
die incl. electronic controls Cost 30 vs
300 bulk sensor (93) Cut to 5/axis by
1998 Replaced by 3-axis ADXL150
Elastic hinge
Proof Mass
Spacer
Force
Silicon substrate
Capacitive Accelerometer
Every new car sold has micromachined sensors
on-board. They range from MAP (Manifold Absolute
Pressure) engine sensors, accelerometers for
active suspension systems, automatic door locks,
and antilock braking and airbag systems. The
field is also widening considerably in other
markets. Micromachined accelerometer sensors are
now being used in seismic recording, machine
monitoring, and diagnostic systems - or basically
any application where gravity, shock, and
vibration are factors.
http//www.analog.com/library/techArticles/mems/xl
bckgdr4.html
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Mass commercial application Pressure Sensors
Pext
Membrane
Measure RC time
Pint
Spacer
Force
Silicon substrate
Capacitive Pressure Sensor
Piezo-resistive pressure sensor
High-pressure gas sensor (ceramic surface-mount)
NovaSensors piezo-resistive pressure sensors
Disposable medical sensor
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Electrical actuation of active MEMS devices
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Surface Micromachining Layer by layer addition
Starting from bare silicon wafer, deposit
pattern multiple layers to form a (shippable)
MEMS wafer
Assembly mechanical manipulation of structures
(e.g., raising and latching a vertical mirror
plate) Various techniques used, some highly
proprietary
From Cronos/JDSU MUMPS user guide at
www.MEMSRUS.com
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1st Optical MEMS device
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Bulk MEMS Fabrication Pattern selective etch
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Bulk Silicon MEMS Devices
Comb-drive switch photo courtesy IMT (Neuchatel)
Single-axis tilt-mirror photo courtesy R. Conant,
BSAC
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MEMS reliability?
MEMS Reliability Infrastructure, Test
Structures, Experiments and Failure Modes 171
page report by D. M. Tanner et al, SAND2000-0091,
January 2000.
Conclusions (1) Properly designed MEMS devices
are remarkably shock resistant (2) Flexural
failures due to fatigue were not apparent (3)
Rubbing wear ( resulting debris) was their
primary failure mechanism
www.sandia.gov
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Optical MEMS Devices Classical vs Resonant
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Classical optical MEMS
1st-surface reflection
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Resonant Optical MEMS
Interference / Diffraction
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Resonant Optical MEMS
Resonant Optical MEMS Tunable Photonic Bandgap
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The MARSResonant MEMS Modulator
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Fabry-Perot etalon reflectivity
Resonant optics Sub-wavelength actuation
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Fabry-Perot etalon spectral uniformity
Resonant Optics Wavelength dependence
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The MARS resonant MEMS modulator
MARS (Membrane Anti-Reflection Switch) analog
optical modulator l/4 Silicon Nitride drumhead
suspended over a Silicon substrate
Goossen, Arney Walker, IEEE Phot. Tech. Lett.
6, 1994
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MARS dielectric multilayer structures
Dielectric Silicon Nitride
Conductive Polysilicon Nitride
Ford, Walker, Greywall Goossen, IEEE J.
Lightwave Tech. 16, 1998
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Lucents MARS bulk MEMS fabrication
Walker, Goossen Arney, J. MEMS 5(1), 1996
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MARS time voltage response
500 um DPOL drum w/ 300 um window has 1.1
microsecond response 110 um SiNx drum w/ 30 um
window has 85 nanosecond response (used for 16
Mb/s digital data modulation)
Ford, Walker, Greywall Goossen, IEEE J.
Lightwave Tech. 16, 1998 Greywall, Busch
Walker, Sensors Actuators A A72, 1999.
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MARS Applications - Data modulator -
Variable attenuator - Dynamic spectral
equalizer - Dispersion compensator (see
references or other presentations)