1. Novel design of a thermo-optic Mach-Zehnder Interferometer(MZI)
with power consumption reduced by one half.
The US Patent #20050048409 comes close to this approach. This is a
design by the Intel Corporation group that used this approach to fabricate a
Bragg grating. In my approach, I will apply a different approach to a MZI and
a VOA and prove that the power consumption of these devices can roughly
be reduced by one half. Currently the theory agrees with computer simulations
using BeamProp and FemLab.
2. Designing the world's fastest thermo-optic modulator.
Abstract from rough draft - below I have the URL to the entire paper.
This personal invention has been informally edited by a faculty member.
Abstract : Recently there have been less attention given to thermo-optic
Silicon on Insulator (SOI) Mach-Zehnder Interferometers switches and
modulators (MZI's) due to the their slow frequencies relative to their
CMOS fabricated counterparts working at higher frequencies using the
plasma dispersion effect. Although the speeds of MZI switches and
modulators have increased within the last five years currently they have
reached a saturation point due to some physical limitations. In this paper
a research model has been derived for a modulator that could overcome
some of these physical limitations to increase speed and also have the
modulator keep up with increasing modulating frequencies as faster and
faster switches are invented. The model described is estimated to work
in lower MHz frequencies attaining the highest possible modulation
frequencies for thermo-optic modulators while proving that power
consumption is lowered significantly.
Entire paper
:
http://sidath.senadheera.net/paper.pdf
3. Using a very robust modulation technique such as PSK ( Phase shift
Keying ) in photonics devices and designing simpler PSK demodulators
This paper will give an outline of the fundamental setup of a unique modulating
and demodulating technique than those currently being used. Dr. Andrew Knights
has informally confirmed the correctness of my approach, but is not responsible
for the details or co-author this publication. The modulation that has been used
in encoding signals to a carrier signal is almost entirely ASK (or AM) Amplitude
modulation. Amplitude modulation is subjected to electronic noise and other
types of defects in the medium that carries the signal like changes in the index
of refraction in the fiber optic cable. On the other hand PSK is not a function
of these defects and noise and therefore a much stronger signal is received after
demodulation with minimum BER (bit error rate) and high S/N ratio. This same
system could be pushed ahead to QPSK where the phase is not just limited
to two, but four different states while doubling the bandwidth. A prototype
this system can be easily built with inexpensive off the shelf material.
Note: As you will see from the attached URL below, last year (2005) five researchers
from the Intel corporation built something like this. But they still used AM modulation
with their new modulation technique. PSK modulation has not been used since the
demodulating end is too complex. In my paper I have worked out more technically
detailed information on this approach using a very simplified demodulator for PSK.
Paper from Intel group :
Note: The 4th reference in the article below is my co-supervisor, Andrew Knights
http://www.opticsexpress.org/ViewMedia.cfm?id=82928&seq=0
4. Change polarization to alter the direction of the TE vector by stress /strain
and modulate a signal.
Stress on a piezoelectric material causes polarization changes. If such a material
is continuously made to change the level of stress in a systematic way, a signal
can be created by changing the angle of electric field vector relative to it's original
vertical direction. In other words flipping the TEoo vector by 0 to 90 degrees the
binary numbers (1,0) can be created. This has already been done in other ways in
CMOS fabricated devices. I will use a novel approach to modulate a similar signal.
In addition since the physical properties of a wave such as phase, polarization,
amplitude are independent of each other, all these three effects can be induced
in the same carrier to form three different modulation schemes at the same time to
carry (3-6) times or more information than what a conventional (ASK or AM)
modulated signal can carry.
5. Design of an intermediate modulation converter from a complex fiber-optic
modulation systems to ASK (AM) operated silicon photonics systems, vice versa.
The next generation of micro-processors and integrated circuits will consist of parts
working with silicon photonics. Companies such as Intel will not introduce the first
silicon photonics integrated devices with complex modulation schemes. Therefore a transition
of a signal modulated under these complex modulation methods that are already being used
today such as ASK/ QPSK/ PO-LSK ( Polarization Shift Keying ) from a fiber optics system
must be able to be converted to a silicon photonics system, vice versa. This paper will describe
why such a conversion is necessary and how such a conversion can be designed with less
attenuation of the signal, without lag,
introduction of error or noise (or low BER and high S/N).
6. All of the first three applications could be combined.
It is possible to put MZI's in parallel as in # 2 and extend this configuration to CMOS
fabricated MZI's functioning under the plasma dispersion effect. This could double or
quadruple the fastest modulators. PSK/QPSK can be used to reduce the signal attenuation.
7. Using Silicon Photonics interferometry to simplify Adaptive Optics.
LINK : gives a crude theoretical
derivation.
It is a common problem having to demodulate a phase modulated (Or phase shift induced)
signal in fiber optic communications. The demodulating end is somewhat complex in these
systems. Silicon photonics provides somewhat of an easier solution by using interferometry.
That is, the incoming wave from the guide star is added to another signal which has the same
frequency (Look at Part I in the link above). Then the intensity of the resultant wave is
measured. It can be written as a function of two phases and amplitude. The added wave
must have a similar amplitude. Or the change in the amplitude as a function of time should
be negligible compared to change in the phase as a function of time. Now the measured
intensity is an addition of two dc offset voltages. One will have a constant value and the other
will be varying (see the end result of PART II in the link above). By taking the magnitude
of the varying voltage at uniform time intervals gives the change of phase in the incoming
radiation. The alterations done in Shack-Hartman Lenslett array are proportional to these
phase changes.
Other technical projects of interest.
* photoconductive radiometry At University of Toronto : (2004-05)
* work on the communication system in Canadian Space Telescope
"M.O.S.T."
* current scientific work, status and
location of MOST in space
*Research work using VLBI for
communication with low powered spacecrafts.
Joint contract project with the European Space Agency (ESA) and
UTIAS/SFL - University of
Toronto
*solutions for multipath fading in bomb disposal robots
.....................Under Construction from here................
*
PCB designs and system designs for IR
imaging and other technical applications (1999).
*Design of infrared imaging systems: for industrial and military applications
(99/00).
* (non-scientific...) - From the University of Waterloo campaign website 2003 ; Far right
*Antenna / Radio telescope related project (1996).
*Research in Solid State Devices (related .pdf document) : At McMaster University, (2005 -06)
Contact : senadhs@univmail.cis.mcmaster.ca
( After 31st August 2006 please use ) sid.senadheera@gmail.com
