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					               ACKNOWLEDGEMENT


I extend my sincere gratitude to Dr.N.Premachandran, principal , Govt.
Engineering College ,Thrissur , and Prof.K P Indira Devi, Head Of the
Electronics and Communication Department, Govt. Engineering college
Thrissur , For providing me with the necessary infrastructure for
successful completion of my seminar.


I would like to convey my deep sense of gratitude to the seminar
coordinator,   Smt.   C.R.   Muneera     .Asst.   Prof,   Electronics   and
communication department for her relentless support.


I am also thankful to Mr.C.D. Anilkumar, Lecturer electronics and
communication department, for his suggestions.


I am thankful to all of my friends for their moral support for me.
SEMINAR REPORT’04            MEMS BASED OPTICAL CROSS CONNECTS




                           Abstract

          Over the few years an amazing amount of interest has
emerged for applications of micro electro mechanical systems in
telecommunications. MEMS devices are beginning to impact almost
every area of science and technology. In fields as disparate as wireless
communications, automotive design, entertainment, and light wave
systems. Continuous growth in demand for optical network capacity
has fueled the development of optical cross connects having high
capacity and reliability. Micro-Electro-Mechanical-Systems devices are
recognized to be the enabling technologies which provide a cost
effective and reliable way to the implementation of these optical cross
connects. Silicon based MEMS have proved to be the technology of
choice for low cost scalable photonic applications because they allow
mass manufacturing of highly accurate miniaturized parts and use
materials with excellent electrical and mechanical characteristics. The
use of MEMS for optical switching has tuned out to be most attractive
since this application could revolutionize fiber optic telecommunications.
While the promises of automatically reconfigurable networks and bit
rate independent photonic switching are bright, the endeavor to
develop a high port count MEMS based OXC involves overcoming
challenges in MEMS design and fabrication       , optical packaging and
mirror control.




            dept. of ece   gec thrissur                                 1
SEMINAR REPORT’04         MEMS BASED OPTICAL CROSS CONNECTS




                          CONTENTS
  1. INTRODUCTION………………………..……………..….03

  2. OPTICAL SWITCHING……………………….……..…..04

    2.1.     ALL OPTICAL SWITCHING..…………………….05
      2.1.1. PLANAR LIGHT WAVE CIRCUITS……………..06
     2.1.2. MICRO ELECTRO MECHANICAL SYSTEMS...06
     2.1.3. INK JET BUBBLE SYSTEMS………….………….06
     2.1.4. ELECTROHALOGRAPHY………….…………..…07


  3. MEMS SWITCHES………………………………………....08
     3.1. ACTUATION METHODS……………………….…....12
     3.2. MEMS SWITCH ARCHITECTURES……………….12
        3.2.1. 2-D ARCHITECTURE…………………………..12
        3.2.2. 3-D ARCHITECTURE…………………….….…14

  4. DESIGN AND FABRICATION…………………………….16
      4.1. DESIGN…………………………………………………16
      4.2 FABRICATION……………………………………..…..17
        4.2.1. MICROMACHINING PROCESS………….……..18
        4.2.2. ELECTRO STATIC MEMS MIRROR……….…..19

  5. PERFORMANCE CHARACTERISTICS…………………..20

  6. APPLICATIONS ….………..…………................................…21

    CONCLUSION ………………….…………….....................…22

     REFERENCES…….……………………..........................…...23



         dept. of ece   gec thrissur                               2
SEMINAR REPORT’04              MEMS BASED OPTICAL CROSS CONNECTS




1.Introduction
            As the modern communications and Internet becomes increasingly
prevalent across the globe, fiber optics - as the defacto infrastructure that
supports the information revolution - is racing to keep up. The demand for
Internet services is driving the growth of data traffic worldwide. Software
developers and users are constantly adopting applications that devour more
and more bandwidth in order to speed delivery of information. As multiple
forms of traffic place increasingly heavy burdens on fiber networks, carriers
are looking for innovative ways to push more data through existing fiber.
       Generally, the current telecom infrastructure is a mix, with fiber optic
cables in the 'core' long-haul backbone networks, some fiber and copper wire
in metro or regional networks, and primarily copper wire for access networks
and 'last mile' connections to customers (though other technologies -- such
as cable, satellite, and fixed wireless -- are also used).
       The Holy Grail in telecommunications and networking today is the 'all-
optical network', where every communication would remain an optical
transmission from start to finish. The speed and capacity of such a network -
with hundreds, if not thousands, of channels per fiber strand -would be
practically limitless.




              dept. of ece   gec thrissur                                    3
2. Optical switching
      Most networking equipment today is still based on electronic-
signals, meaning that the optical signals have to be converted to
electrical ones, to be amplified, regenerated or switched, and then
reconverted to optical signals. This is generally referred to as an
'optical-to-electronic-to-optical' (OEO) conversion and is a significant
bottleneck in transmission. Huge amounts of information traveling
around an optical network needs to be switched through various points
known as nodes. Information arriving at a node will be forwarded on
towards its final destination via the best possible path, which may be
determined by such factors as distance, cost, and the reliability of
specific routes.
           The conventional way to switch the information is to detect
the light from the input optical fibers, convert it to an electrical signal,
and then convert that back to a laser light signal, which is then sent
down the fiber you want the information to go back out on. For example,
in a long-haul network, an OEO conversion may occur as often as
every 600 kilometers just for amplification purposes. The basic premise
of Optical Switching is that by replacing existing electronic network
switches with optical ones, the need for OEO conversions is removed.
           The advantages of being able to avoid the OEO conversion
stage are significant. First, optical switching should be cheaper, as
there is no need for lots of expensive high-speed electronics. Removing
this complexity should also make for physically smaller switches.
Unfortunately, optical switching technology is still very much in its
infancy.
SEMINAR REPORT’04             MEMS BASED OPTICAL CROSS CONNECTS


            There have been numerous proposals as to how to
implement     light    switching    between     optical   fibers,     such    as
semiconductor amplifiers, liquid crystals, holographic crystals, and tiny
mirrors. In spite of recent market performance of some very important
telecom stocks, the international telecommunications network is poised
for another enormous advance by providing additional capacity and
services with reduced costs.
            Optical cross connects will soon permit optical traffic to pass
through crowded intersections with no conversion required. Optical
switches of many types will facilitate pure optical switching and
add/drop multiplexing in metro networks and in support of restoration,
maintenance           and    testing                                            .

2.1. ALL OPTICAL TECHNOLOGIES
          Dozens of telecom systems companies and suppliers
continue to offer OEO systems while keeping an eye on and supporting
pure   optical-switching      technology       developments.        All   optical
technologies are those in which the electrical to optical conversion is
avoided and     the     switching is   done    completely    in the       optical
domain.
            Most of the technologies adopted by promising candidates
come from the integrated circuit (IC) industry. Planar light wave circuits
(PLC), micro electro mechanical systems (MEMS), ink-jet bubble
technology,      liquid-crystal     systems,      electroholography,         and
thermoelectric techniques are some of the technologies currently under
development.
          These IC-based systems bring mass production, repeatable
quality, and lower manufacturing costs than current practice. Switches
and cross connects based on these technologies will perform
transparent switching in which traffic stays in the optical form all the
way through the network backbone and down into the metro.



            dept. of ece    gec thrissur                                       5
 SEMINAR REPORT’04           MEMS BASED OPTICAL CROSS CONNECTS




 2.1.1. Planar light wave circuits


           Planar light wave circuits take advantage of IC practice in that
 layers of material are deposited and etched to create channels for
 either diverting or passing photons. The wall material of the channels
 can be reflective on command but there are no moving parts.
           Azanda, Kymata, Light wave Microsystems, Lynx Photonics,
 Nanovation, Network Photonics, OptXcon, and Optical Switch Corp. are
 some of the startups developing PLC technology.



 2.1.2. Micro electro mechanical systems


           Micro electro mechanical systems(MEMS), as they apply to
 optical switching, are based upon IC practices that result in a movable
 reflective surface or mirror, the angle of which can be changed by the
 application of electrical power or thermal change. The optical
 wavelength is directed at the reflective surface, which, upon command,
 permits the photons to pass, or diverts them to another exit.
           Astarte, C-Speed, Calient, IMMI, OMM, K2 Optronics,
 Luxcore, Lucent technologies and Onix Microsystems are some of the
 MEMS-based firms.



2.1.3. Ink-jet bubble systems


            dept. of ece   gec thrissur                                  6
SEMINAR REPORT’04             MEMS BASED OPTICAL CROSS CONNECTS




            Ink-jet bubble systems are also IC-based, with the addition
that a microscopic amount of a liquid is placed at each intersection of
etched channels. With the onset of an electrical pulse the liquid is
instantly heated, creating a bubble that is reflective and diverts the
photons to another exit. Agilent and Alcatel are pioneering this
technology.

2.1.4.     Liquid-crystal systems


         Liquid-crystal systems are also IC-based. Polymeric materials
are suspended in special liquids. The materials change their alignment
upon the addition of electrical power—either permitting light to pass
through or diverting it.
            Chorum and Spectra-Switch are two of the leading liquid-
crystal developers.


2.1.5.electroholography                                                   i


            Electroholography is based upon special micro crystals that
can have a hologram stored in them. The hologram is of such a nature
that it allows photons to pass through when it is in the 'off' position and
is reflective when in the 'on' position, thereby diverting the light upon
command. Trellis is currently developing this technology.




             dept. of ece   gec thrissur                                 7
SEMINAR REPORT’04            MEMS BASED OPTICAL CROSS CONNECTS




3. MEMS SWITCHES
          In telecom, MEMS has become synonymous with the arrays
of tiny tilting mirrors used for optical switching fabric, although the same
technology is being used to make a wide range of other components as
well. MEMS consist of mirrors no larger in diameter than a human hair
that are arranged on special pivots so that they can be moved in three
dimensions.
          Several hundred such mirrors can be placed together on
mirror arrays no larger than a few centimeters square. Light from an
input fiber is aimed at a mirror, which is directed to move the light to
another mirror on a facing array. This mirror then reflects the light down
towards the desired output optical fiber.     Since MEMS creates so
many mirrors on a single chip, the cost per switching element is
relatively low. However, since it involves moving parts, MEMS is fairly
slow to switch – requiring milliseconds to do so. This is fine for lambda
provisioning or restoration but is too slow for optical burst switching or
optical packet switching applications.
      Conventional MEMS works by reflecting the beam of light from
the surface of a tiny mirror.The micro mirrors are actuated by



            dept. of ece   gec thrissur                                   8
SEMINAR REPORT’04            MEMS BASED OPTICAL CROSS CONNECTS


electrostatic actuators, which are located behind the reflecting front
face of the mirrors.
      MEMS systems have moving parts, and the speed at which the
mirror moves is limited. By applying more current, the mirror can move
faster, but there's a limit to how much current can be sent into the array
of mirrors. If this weren't bad enough, it seems that the speed and
angular displacement terms in the calculation of the required current
have integer powers of around 4 or 5, and so the bottom line is that we
have to put a lot of current into the array for a small improvement in
speed.
          By changing the mirror design so that the angle through
which light is bent is smaller, it's possible to achieve faster switching
speeds. This technique is known as "fast MEMS."
      MEMS arrays can be built on a single-chip, single-plane
approach. In other words they are 2 dimensional (2D MEMS). In a
simplistic approach it‘s also possible to stack a number of 2D MEMS
arrays on top of each other to create a 3D MEMS array. In fact, real 3D
MEMS systems are somewhat more complex than this, but the general
principle holds.
           A huge drawback of 3D MEMS is the fact that the thousands
of mirrors require complex software to coordinate their operations.    In
particular, one vendor has suggested that there are over a million lines
of code in their implementation (although the reference may be to the
overall switch software, and not just the MEMS subsystem). While it‘s
possible to test software extensively, the opportunity for bugs increases
geometrically with the size of the code base. On the upside, MEMS is a
very rapidly changing technology.
           Since it seems to have a monopoly on the high port-count
optical switch market for the moment, a huge amount of investment is
going into the implementations and into solving the basic problems.




            dept. of ece   gec thrissur                                 9
SEMINAR REPORT’04         MEMS BASED OPTICAL CROSS CONNECTS




                  Fig. 1 MEMS Mirror Array




         dept. of ece   gec thrissur                          10
SEMINAR REPORT’04              MEMS BASED OPTICAL CROSS CONNECTS


Micro Electro Mechanical Systems (MEMS) are semiconductor-made
micro-mechanisms, which are generally used as movable micro-mirrors
that can deflect optical signals from input to output fibers. As far as
medium- and large-size switching fabrics are concerned, micro-mirrors
can be arranged into two-dimensional or three-dimensional arrays . In
these switches, mirrors are steered in order to deflect light beams
properly. Small-size switches          can be also made, as shown in the
following figure




                             Fig.2 MEMS Switch



      In this case, the mirror slides along the 45° direction, yielding the
BAR or CROSS states. MEMS switches feature good scalability.
MEMS research is an outgrowth of the vast capabilities developed by
the   semiconductor        industry,   including   deposition,   etching,   and
lithography, as well as an array of chemical processes such as
anisotropic and highly selective etches having different etch rates for
different crystallographic orientations and materials. These processes,
which were originally developed to build microelectronics, are also
capable of building micromechanical devices (structures capable of
motion on a microscopic scale).



            dept. of ece     gec thrissur                                    11
SEMINAR REPORT’04            MEMS BASED OPTICAL CROSS CONNECTS


          MEMS are built in much the same way as a silicon integrated
circuit. Various films such as polysilicon, silicon nitride, silicon dioxide,
and gold are deposited and patterned to produce complicated,
multilayer three-dimensional structures. However, the major difference
is a release step at the end. Ina MEMS device, some of the layer
materials are removed using a selective etch, leaving a device with
elements that can move. The advantages                  of batch-processing
techniques such as cost minimization make it economical to produce
such optical cross connect switches
          The mirror is connected to a see-saw and either reflects the
light from the optical fiber on the left to the fiber at right angles to it, or
moves out of the way to allow the light to go straight into the other fiber.




Fig. 3 A two-axis micromirror for use in an all-opticalcrossconnect


          Shown in the above figure is a two-axis micro mirror for use in
an all-optical cross connect. The mirror is doubly-gimbaled so that light
can be routed in two directions to allow complex switching functions to
be performed. Such mirrors have enhanced the manufacturing of large,
MEMS-based, optical cross connects.
          These switches have very large port counts, low losses, fast
switching speed, and low costs. Clearly, the possibilities for novel
optical devices and functions are endless.


            dept. of ece   gec thrissur                                     12
SEMINAR REPORT’04             MEMS BASED OPTICAL CROSS CONNECTS


3.1. ACTUATION METHODS OF MEMS MIRRORS


      Magnetic actuation and electrostatic actuation are the two viable
choices for mirror positioning.
          Magnetic actuation offers the benefit of large bidirectional
(attractive and repulsive) linear force output but requires complex
fabrication process and electromagnetic shielding .
          Electrostatic     actuation      is   preferred   method   for   mirror
positioning because of the relative ease of integration and fabrication..
They consist of four capacitor pads separated by two orthogonal
channels parallel to the two axes of rotation of the corresponding micro-
mirror. The mirror is grounded and the four pads are placed under a
bias voltage to mechanically preload the mirror. By modulating the
voltage of the four pads about the bias level it is possible to generate
controlled rotations of the micro-mirrors.



3.2. MEMS Switches Architectures

      Switch arrays are constructed from multiple switch elements. The
arrangement usually follows one of                 three configurations: two-
dimensional (2-D) matrices of NxN two-position mirrors, linear arrays of
NxN single-axis multiple-position mirrors [three–dimensional (3-D)
1xNarrays]

3.2.1. 2-D ARCHITECTURE

      Fig. 4 shows the arrangement of the first type of cross connects.
The inputs are provided by a linear array of optical            N fibers. Light
emerging from the fiber array is collimated by a linear array of lenses
into a set of quasi-parallel beams that propagate in free space. The



             dept. of ece   gec thrissur                                      13
SEMINAR REPORT’04             MEMS BASED OPTICAL CROSS CONNECTS


outputs are taken from a similar array of fibers, equipped with a similar
set of lenses, and designed to accept a similar set of beams. The axes
of the input and output fibers are typically arranged at right angles.




Fig .4 principle of NxN mirror insertion free space optical cross connect




Fig .5 Illustration of NxN mirror insertion free space optical cross connect
                      (2-D Architecture)
           The space between the input and output fiber arrays is filled
with a set of small movable mirrors, capable of being inserted and


            dept. of ece   gec thrissur                                        14
SEMINAR REPORT’04            MEMS BASED OPTICAL CROSS CONNECTS


removed from the intersections between the beams at an angle
intermediate between their directions. A path between           i-th input fiber
and j-th output fiber is then established by the insertion of the relevant
mirror M(i,j).

3.2.2. 3-D ARCHITECTURE
Fig.6 shows the second type of cross connect. The inputs and outputs
are again linear arrays of N fibers equipped with collimators. However,
between the input and output, the beams are reflected from two linear
arrays of mirrors.




    Fig 6. Principle of NxN mirror rotation free space optical cross connect




          Each individual mirror may be rotated through a variable angle
about an axis normal to the figure. A path between input fiber and
output fiber is then established by angular adjustment of mirror from the
first array and mirror from the second, in a periscope configuration.
NxN cross connects have been constructed using MEMS mirrors on
torsion suspensions




            dept. of ece   gec thrissur                                        15
SEMINAR REPORT’04              MEMS BASED OPTICAL CROSS CONNECTS




     Fig .7.illustration freespace optical cross connect (3-D Architecture)


         A similar principle is used in the third type of cross connect. The
linear arrays of         N fibers and collimators each replaced with 2-D
arrays of     N square           fibers and collimators, and the linear arrays
of   N       single-axis mirrors are replaced by 2-D arrays of        N square
dual-axis mirrors. The required mirror motion is achieved by mounting
the mirror on a gimbals suspension, as in Fig. 7. This type of switch is
scalable to a higher port count, and has been demonstrated using
several forms of MEMS mirror




              dept. of ece   gec thrissur                                     16
SEMINAR REPORT’04               MEMS BASED OPTICAL CROSS CONNECTS




4. Design & Fabrication
      Components of a large MEMS based OXC system include
thousands of actuated mirrors, lenses and collimator arrays. With no
doubt the MEMS mirrors, the key active element in the optical system, is
the most critical technology for large OXCs


4.1. Design

          A two axis tilting mirror can be divided into three elements: the
mirror, the springs as the mechanical support and the actuator all of
which determine the important OXC system parameters such as
insertion loss, settling time, and maximum port count and power
dissipation.


          Reflectivity of each mirror is desired to be above 97 percent.
The tilt angle requirement varies from a few degrees to 10 degrees on
either direction depending on the design.


          Challenges in design come from the different trade-offs
between desired properties of the MEMS device. As an example the
stiffness of the supporting springs should meet the mirror response time
and the mirror stability and immunity to shock. But the maximum
stiffness is determined by the maximum tilt angle and the actuators
maximum force or torque output as well as the system power budget.




               dept. of ece   gec thrissur                              17
SEMINAR REPORT’04            MEMS BASED OPTICAL CROSS CONNECTS


           A stable metal coating such as gold, along with necessary
additional metal adhesion and diffusion barrier layers is often used as
the reflective surface. These metal coatings can create an undesirable
temperature dependent mirror curvature due to intrinsic stress of the
metal layers and the difference in the temperature coefficients of the
metal coating layers and the bulk mirror made up of a different material.
This problem is severe if the coating is applied only to one side of the
mirror. A thick mirror can counteract all these difficulties but then the
mass of the device increases prohibitively.



4.2. Fabrication


           In principle the bulk mirror can be made of any material as
long as reliability, reflectivity, and optical flatness requirements are met.
Single crystal silicon, commonly used in MEMS, is recognized to be the
most suitable technology over polysilicon or electroplated metal due to
low intrinsic stress and excellent surface smoothness. The choice of the
material for the mirror springs is even more important because the
mirror springs will be constantly subject to twists and bends.
           Superior mechanical characteristics make SCS a strong and
the best candidate for the mirror springs. Alternative material such as
polysilicon are poor substitutes because of potential stress,hysterisis
and fatigue problems. n most cases ,the same material is chosen for
both the mirror and springs in order to yield a straightforward fabrication
process.
           Besides typical lithography, deposition, and etching procedures
necessary    fabrication   steps     include   deep   reactive   ion   etches
(DRIE) .silicon wafer bonding and chemical mechanical polishing (CMP).
           Silicon on insulator (SOI) wafer is a convenient starting
material for the SCS bulk mirrors with uniform thickness           and low


            dept. of ece   gec thrissur                                   18
SEMINAR REPORT’04             MEMS BASED OPTICAL CROSS CONNECTS


intrinsic stress but they are expensive. Applying clever silicon etching
and wafer bonding techniques to cost effective silicon wafers may also
yield mirrors with sufficiently large ROC(radius of curvature ) and low
mass. the primary differentiating factor between these MEMS mirror
processes     is   device      performance   characterized    by   mirror
size,flatness,reflectivity ,maximum tilt angle and ease of mirror control.
Material supply availability, length of fabrication cycles equipment
bottlenecks play important roles in shortening product development
cycle time to market.
          Ease of circuit integration mirror array size and manufacturing
yield may also influence the overall switch fabric design. Arguably , a
fabrication process that enables monolithic integration of electronics
with MEMS may lead to MEMS mirrors with highest performance and
greatest functionality.


4.2.1. Micromachining processes used to

      Build MEMS devices




            dept. of ece    gec thrissur                                19
SEMINAR REPORT’04             MEMS BASED OPTICAL CROSS CONNECTS




   Fig .8. the micromachining process for making the mirror.




4.2.2.      Illustration of an SOI based
             Electrostatic MEMS mirror




         Fig 9(a) before release of gimbaled mirror




             dept. of ece   gec thrissur                          20
SEMINAR REPORT’04          MEMS BASED OPTICAL CROSS CONNECTS




     Fig 9(b) after release of gimbaled mirror




                Fig 10      Single MEMS mirror for OXC




         dept. of ece    gec thrissur                          21
SEMINAR REPORT’04               MEMS BASED OPTICAL CROSS CONNECTS


5. Performance Characteristics
       The following are some performance paramters of optical switches.
(1)    The wavelength range
       it is the range of the wavelengths that can be routed without much
       tioattenuan .it is ussually expressed in nanometers

(2)    insertion loss
       it is the attenution introduced to the signal due to the insertion of
       the device.it is expessed in dB

(3)    cross-talk attenuation


       the attenuation encountered to the undesired light waves is
       known as cross talk attenuation.it is measured in dB and
       should be as high as   possible


(4)    power dissipation
       it is the power consumed by the associated contrl circuitry for
       positioning the mirror in the proper direction and is measued in
       mW

       and
(5)    switching time
       it is also called the latency,and is the time between applying the
       control signal and the establishment of the connection.measured
       in ms
6. Applications
       optical switches can be used in a wide range of applications such as
those given below.
Optical switching.
       Optical switches can be used as basic building blocks for network
nodes to provide optical circuit or packet switching.   Switching times in the
ms range are sufficient for circuit switching. Nevertheless, to the purpose of
optical packet switching, switching times in the ns range are required.
Optical add-drop multiplexing


             dept. of ece   gec thrissur                                   22
SEMINAR REPORT’04            MEMS BASED OPTICAL CROSS CONNECTS


           Optical add-drop multiplexers are used to add and drop
specific wavelengths from multi-wavelength signals, to avoid electronic
processing. For this application, wavelength selective switches are
required. Switching times in the ms range are adequate.
Fiber restoration and protection switching.
      Small-size switches are used to restore optical paths in the event
of link failure. For this application, 2x2 switches, with switching times in
the ms range, are commonly used.
Signal monitoring
       For ease of network management, optical switches can be used
for signal monitoring. To this purpose, wavelength-selective switches
are commonly used.




                     CONCLUSION

          MEMS technology offers tantalizing possibility of advanced
optical cross connects with large port count, scalability, and switching
capacity that can meet the switching demands in the ever faster, denser,
rapidly growing optical networks today and in the future. Of course,
further research and development that considers not only device
performance but also reliability and total cost, including both fabrication
and maintenance, mirror control algorithm will be necessary when
applying these devices to optical cross-connects and optical add/drop
multiplexers. As MEMS technology continues to advance ,one thing
is clear , The powerful        impact     of MEMS technology        for the
telecommunications industry will never be forgotten.




            dept. of ece   gec thrissur                                  23
SEMINAR REPORT’04               MEMS BASED OPTICAL CROSS CONNECTS




                              REFERENCES

1. 'The lucent lambda router: MEMS technology of the future here
     today '
       David J Bishop Randy Giles, Gary p Austin, Lucent technologies
      IEEE Communications magazine MARCH 2002, Vol.40, No. 3


2.     Lucent Technologies, ―Lambda Router™ All Optical Switch,‖
       http://www.lucent.com/products/solution


3.     MEMS Optical, ―Scanning Two Axis Tilt Mirrors,‖



               dept. of ece   gec thrissur                              24
SEMINAR REPORT’04              MEMS BASED OPTICAL CROSS CONNECTS


      http://www.memsoptical.com/prodserv/products/twotiltmir.htm.


4.    'Micro-Mirror Array Control of Optical Tweezer Trapping Beams.'
      Nicholas G. Dagalakis, Thomas LeBrun, John Lippiatt.
      National Institute of Standards and Technology
5.    www.sercalo.com


6.    'SPIE‘s International Technical Group Newsletter ' DECEMBER
2000


7.    'Silicon micro machines'
      David Bishop, Vladimir Aksyuk, CrisBolle, Randy Giles,
      and Flavio      Pardo
       Micromechanics Research, Bell Laboratories
      Lucent Technologies, Murray Hill




8.    'Modular MEMS-Based Optical Cross-Connect With Large Port-
       Count'
     N.Bonadeo, T. Chau, M. Chou, R. Doran, R. Gibson. Harel,
      IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 15, NO. 12,
     DECEMBER 2003.


9. 'A Technical Paper: Discussing Optical Phased Array Technology
     For    High- Speed Switching ‗ ,       Chiaro Networks whitepaper
     http://www.chiaro.com/pdf/chiaroleos2002.pdf


10. ' Integrated Modeling of Optical MEMS Subsystems'
      Robert Stoll, Thomas Plowman, David Winick, Art Morris Coventor,
     4001     Weston Parkway, Suite 200, Cary, NC 27513


              dept. of ece   gec thrissur                                25
SEMINAR REPORT’04         MEMS BASED OPTICAL CROSS CONNECTS




         dept. of ece   gec thrissur                          26

				
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