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Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
O-MEMS Fiber SwitchesOlav Solgaard
Stanford University• Motivation• Fiber switch concepts
2x2 switch Matrix switch 3-D switch
Scaling Experimental demonstrations
Challenges Optical quality, large switches,
reliability, speed, fiber alignment, packaging…….
Network impact Packet switching?
• Conclusions
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Beam Steering Optical Switch
lkNs 2
I n p u tf i b e ra r r a y
O u t p u tf i b e ra r r a y
Analog mirrors 2N scaling Lucent, C-speed,
Xros(NT),.....
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Fresnel Zone Lens
Fresnel Zone plate on polysilicon plate, which is rotated out of the plane on microhinges. The fact that the lens is an amplitude grating limits its diffraction efficiency. Lin, Lee, Pister, Wu, UCLA, 1994.
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
2 x 2 fiber-optic switch
Compact design One-mask fabrication
using DRIE on SOI Integration of fibers,
lenses, and micromirrors
2 by 1 operation By-pass switch AT&T, JDSU.......
In 1
In 2
Out 2
Out 1
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
1 x 2 Matrix Switch
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
2x2 switch – DRIE of SOI
manipulator
comb drives
Fiber grooves orchannels
Springs
Bryant Hichwa etal, OCLI/JDS Uniphase, “A Unique Latching 2x2 MEMS Fiber Optics Switch”, Optical MEMS 2000, Kauai, August 21-24 th, 2000.
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
DRIE etched vertical micromirror
Pro: Simple fabrication (one
masking step) Simple packaging
Con: Scaling Large device count Immature fabrication
processes (reliability)
C. Marxer, N.F. de Rooij, Jrnl of Lightwave Tech., Vol. 17, No. 1, Jan 1999
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
NxN Matrix OXC
Simple 1 by 2 cross-points
Digital mirrors N2 scaling Large motion Reliability?? OMM, Onix, AT&T,
Agilent.....
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Waveguide Cross Connects
TIR cell
Single mode optical waveguides
Champagne Switch (Agilent)
Input Straight through
Switched Output
Vertical directional coupler
Vertical Directional Coupler
S. Yu, M. Owen, R. Varrazza, R.V. Plenty, I.H. White, “High speed optical packet routing demonstration of a vertical coupler cross point switch array”, Proceedings of the Conference on Lasers and Electro-optics(CLEO), San Francisco, May 7-12, 2000, pp. 256-257
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
AGILENT’s NxN OXC based on InkJet Technology
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Micromachined tilt-up mirrors
TORSIONALHINGE
100 m
COMB DRIVE
TORSIONALHINGES
100 m
COMB DRIVES
Fast-mirror design Slow-mirror design
For 15 degrees optical deflection:Fast mirror: 36.1 Vrms at 4.6 kHzSlow mirror: 60 Vpp below resonance
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Coupling chip
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Diode-laser display
CCD camera
Laser-diodearray
Scanningmicromirror
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Video Display System Based on Microscanners (TV on a chip)
Computer controls the laser diode and both scanning mirrors
The laser beam hits the fast scanning mirror,
... is imaged onto the slow scanning mirror,
…and the image is projected onto the screen
Surface micromachined,
flip-up scanning mirror
1f
1f
2f
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Single-chip scanner layout
633nmHeNe Laser
Mirror Curvature Compensation Optics
Output Optics
Camera
Spatial Filter
Acousto-Optic Modulator
Fast mirror
Output mirror Slow mirror Single-Chip
Raster-Scanner
MechanicalShutter
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Micromachined raster-scanner
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Two-chip scanner images
a d
e
c
f
b
g h
Resolution: 62 by 66 pixels, optical scanning angles 5.3 and 5.7 degrees Acousto-optic modulator switches the laser light off during mirror wobble.
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Large Arrays
Texas Instrument’s DMD
NASA's Next Generation Space Telescope (2008) with 4M micromirrors by Sandia NL
Lucent’s Optical X-Connect
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
System on a chip
Laser-to-fiber coupling
Micropositioners of mirrors
and gratings
High-resolution raster scanner
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Grating Light Valve
1991 Polysilicon hinge (Pister, Judy, Burgett, Fearing)
1992 Grating light modulator (Solgaard, Sandejas, Bloom)
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
UNIQUE FUNCTIONALITY
Silicon Dioxide
Silicon Nitride
Silicon Substrate
25 to 100 µm
Top electrode• Diffractive micro optics• Adaptive micro optics• Configurable holograms• Photonic Crystals• Applications:
1-D and 2-D spatial light modulators (Projection displays - Silicon Light Machines)
Displacement sensors (AFM arrays - C. Quate)
IR sensors Sensor integration, free-space
communication Diffractive lenses and holograms
(Fresnel zone plates - M. Wu, UCLA)
Spectroscopy
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Grating Light Modulator
Silicon Dioxide
Silicon Nitride
Silicon Substrate
Individual ribbons are from 1 to 2 µm wide and from 25 to 100 µm long.Top electrode
Substrate electrode
Beams up, reflection
Beams down, diffraction
Cross section
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
High-contrast GLM
Dark State Bright State
sinon sinoff
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
High Speed Switching
•L
ight
Out
put
20 nsec Switching Speed
time
down
up
GLV devices switch in as little as 20 nsec (~1,000 times faster than TI DMD)
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Grating Light Valve Technology
GLV
Basic Projection System
• Advantages:
• Traditional light source and projection system
• Disadvantages:
• 2-D Addressing
• Large Array =>Low yield
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
SEMs of Grating Light Valve
1-D Grating Light Valve with Silicon nitride ribbons. The detailed picture shows the termination of the ribbons and the addressing lines. Courtesy Silicon Light Machines.
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
GLV Device Reliability
• Ribbon material is Silicon Nitride — a stable ceramic material
• Device operates at small fraction of material’s tensile breaking stress
• Ratio of [ribbon length]:[max deflection] is about 800:1• No contact between ribbon and substrate
2
2.25
2.5
2.75
3
0 1 2 3 4 5 6
1012 Ribbon Cycles
Nat
ura
l F
req
uen
cy (
MH
z)
• Negligible change in natural frequency after equivalent of 10,000 hours of television use
Courtesy of Silicon Light Machines
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
GLV Pixel Fundamental Contrast
Applied Potential (v)
0.3 1 2 3 4 5 6 7 8 1012 15
Opt
ical
Det
ecto
r Res
pons
e (V
)
0.0001
0.001
0.01
0.1
1
~0.125 mV
~325 mV
~ 2600:1 Contrast>2000:1 contrast at the GLV device
Courtesy of Silicon Light Machines
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
The Scanned GLV Architecture
Relative to Scanned Beam (CRT)
1,000X lower channel bandwidth
Natural gamma, smoothly blended images
Variable aspect ratios without light loss
Relative to 2-D Panel
2,000X fewer pixels, smaller silicon die size
Retains high optical MTF
No “screen door” effect
Courtesy of Silicon Light Machines
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
GLM Characteristics
• Small (/4) required deflectionHigh SpeedGood heat dissipation
=> high power-handling capability1-D implementation & simple structure
=> High YieldCMOS “compatible”
=> Inexpensive, flexible fabrication “On-chip” interferometer Good reliability
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
MEMS Phased Arrays
Linear array of piston-motion mirrors for beam steering. Each micromirror is 110 m long and 27 m wide. D.M. Burns and V.M. Bright 1997.
Optical MEMS in communication
and sensing
Copyright O. Solgaard, 2001. All federal and state copyrights reserved for all original material presented in this course
Variable Blaze Grating
Variable Blaze grating with torsional hinges for tilting of each element in the array. Burns, Bright, and Gustavson 1997.