Applications of SOI Based Optical MEMS in Fiber
-
Upload
anant-raj-singh -
Category
Documents
-
view
222 -
download
0
Transcript of Applications of SOI Based Optical MEMS in Fiber
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
1/14
Applications of SOI based optical
MEMS in fiber opticscommunication and others
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
2/14
Key features of MEMS technology
Array ability: which is the term that we use for
the ability to place tiny devices in large-scale
arrays
Reconfigurability: i.e. the ability to reconfigure
the optical properties, spatially and temporally,
via localized micro-actuation and/or deformation
Nanopositioning: nanoscale precision control ofposition and alignment for microscale devices
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
3/14
Optical-MEMS or MOEMS
Three Technologies coming together
Micro-optics:Semiconductor Laser Waveguide
Micro-mechanics:Resonant Gate transistor
Micro-Electronics:IC fabrication
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
4/14
In OFC
There are four main domains:
Amplifiers
Switches or Optical Cross Connectors (OXC) 2x2, 4x4, NxN
Variable Optical Attenuators (VOA)
Filters
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
5/14
Overview of Silicon on Insulator (SOI)
Technology Polycrystalline silicon on top of the buried
SiO2 layer (100mm -2m -75 m)
Photolithography: Patterning anddepositing
DRIE: narrow structures of about 2m to
5m can be achieved with very smoothsidewalls.
The buried SiO2 serves as etch stop forDIRE as etching rate is different indifferent directions
The resist is removed by oxygen plasma
etching. Buried Sio2 is removed by etching with 50%
conc HF acid
SiO2 pedestals remains serves asinsulators between different electrodes
Deposition of Gold for conductivity andproper reflection of mirror.
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
6/14
2x2 optical switch
Two input two output fibers in 75um high grove
Their endfaces all meet at one point,where a movable gold-coated mirroris located. This way, the light of
either one of the input fibers can beswitched to either one of the outputfibers
Refractive index matching fluid:reduces two effects: first the Index stepbetween the fiber endfaces and theambient and Secondly the divergence of
the freely propagating light; hermeticallysealed
The mirror is attached to a longbeam which is electrostatic allyactuated by comb drive
The optical and mechanical properties
of the switch are
excellent. The insertion loss is between
0.3 and 0.5dB.
The switching time is about 500s
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
7/14
Electrostatic Comb drive Actuators
Driving Principle:
Electrostatic force
generated when voltage
is impressed between
both sides of the comb-
drive electrodes
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
8/14
---Polyimide is used as the structural
material. Since polyimide is an insulator,which cannot be driven electrostatically
by impressed voltage if it is left as it is,
depositing a metallic membrane on
polyimide
---- The structure is the one that supports the
fixed electrode by the anchor of the electrode.
This structure makes it possible to insulate the
fixed electrode and the movable electrode
because the metallic membranes cannot be
formed in the shadow parts of fixed electrodeswhen metals are accumulated from the upper
direction by a sputtering technique after
fabricating the actuator structures
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
9/14
Fabrication
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
10/14
4x4 switch design
Consists of 16 2x2 MEMS switches that will beoptically interconnected by integrated opticalwaveguides
Top chip holding the waveguides and the electricalconnections for the switches. The two chips will becombined by standard flip chip bonding technology.
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
11/14
Variable Optical Attenuators (VOA) Losses due to absorption,
bending, scattering
Amplification wavelength
dependent
Channels are split of different
intensities
WDM-VOA-WM
MEMS based VOA: A mirror that
is rotated by 82 to the axis of
light propagation can move
linearly between two opposing
fibers that are held by small leaf
springs in two U-grooves. The
slight tilt prevents the backreflection into the input fiber.
The attenuation efficiency
versus the driving voltage is
depicted.
Not linear hence has to be
calibrated before use.
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
12/14
Fourier transform spectrometer
FT spectroscopy is used for
week and extended sources
High cost; miniature
reduced cost
FTS are based on MichelsonInterferometer configuration
with scanning mirrors.The output signal of the interferometer is the
variation of the light intensity IR as a function
of the opticalpath length d. The relation ofIRto d is referred to as the interferogram. The
wavelength power spectrum and the recorded
interferogram IR(d) are related by a Fourier
transformation. Therefore, a spectrum of a
light source can be obtained by simply
recording IR(d) and a subsequent FT.
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
13/14
MEMS based Accelerometer
The optical source is an LED
The optical detection utilizes the partial and simultaneous lightcoupling from one source fiber into two output fibers
The light of the source fibers hits the point of a V-shaped mirror,which splits and couples the light evenly into the two identicaloutput multimode fibers
The output fibers guide the light to two photodiodes allowingdifferential measurement of optical fiber.
-
8/7/2019 Applications of SOI Based Optical MEMS in Fiber
14/14
Advantages of Optical MEMS
More sensitive than electrical sensors based
systems
Higher dynamic range Free from electromagnetic and electrical
interference noises
Thermal Mechanical noise is negligible High arability due to miniature in size
Nano-positioning, very precise