Here is a listing of a few
of our current research projects. Each link provides a
short description of the work along with any recent results.
Ultrashort Pulse Processing and Detection:
Fiber-Optic
Channel Modeling and Coding Most optical communication research in the past has
been aimed at novel optical components and devices, with
limited attention devoted to establishing realistic models
of the communication channel that consist of not only the
point-to-point optical fiber links but also include optical
network systems elements such as amplifiers, filters, and
multiplexers/demultiplexers. Previous research in compensation
techniques for optical channels has also been limited in
scope because it did not consider both random and nonlinear
channel characteristics. A unique feature of our approach
is to combine cutting edge research in electronic signal
processing and coding techniques with novel
optical domain processing of the phase of the optical signal.
Measurement
of Multimode Fiber Optical Impulse Response
Multimode optical fibers have great
potential for information transmission. In addition to wavelength
degree of freedom currently utilized in single-mode fibers,
multimode fibers possess two additional spatial coordinates
that can be used as additional degrees of freedom to increase
the channel capacity for optical communication.
We employ space-time characterization technique, based on
spatial heterodyne interferometry to analyze propagation
of optical pulses in multimode fibers in space and time.
Instantaneous
Processing of Ultrafast Waveforms
Ultrafast phenomena in the natural sciences can be excited,
manipulated and observed with tailored ultrashort optical
pulses. These ultrafast waveforms are synthesized and processed
in the temporal frequency domain by spatially dispersing
the frequency components in a spectral processing device
(SPD) and performing operations on the spectrally decomposed
wave1 (SDW).
Space-Time
Optical Signal Processing
We investigate optical space-time processors that are
capable of converting (or encoding) a parallel optical
data array into a sequence of pulse trains and vice versa.
Space-time optical conversion is accomplished by nonlinear
optical wave-mixing of spatial and temporal optical signals
in a nonlinear optical medium.
Optical
Storage Three dimensional (3-D) optical
memories enable higher capacities and bandwidth by extending
storage into the third dimension. Our research efforts
include the search for new storage materials, to investigation
of various recording and reconstruction techniques employing
femtosecond pulse lasers.
Photonic Nanostructures: Near-field
Scanning Optical Microscopy (NSOM) Nanofabrication is commonly
addressed using well established microelectronics fabrication
techniques, leading to the construction of fabricated nanophotonic
materials and devices including form birefringent nanostructures,
dispersive nanostructures, resonant photonic crystal nanostructures,
photonic crystal nanostructures with defects, and quantum
dot structures. We have developed a technique for visualization,
imaging, and characterization of nanophotonic devices, based
on coherent Near-field Scanning Optical Microscopy (NSOM)
that allows detection of the complex amplitude of the optical
near-field utilizing heterodyne detection.
Near-field
Localization Nanostructures
AVI movie simulations of ultra-short
pulse propagation through 1-D multi-layer sub-wavelength
structures with strong transverse field localization.
Micro-Polarizing
Beam Splitter
AVI movie simulations of ultra-short pulse propagation through
multi-layer sub-wavelength grating polarizing beam splitter
structures. Artificial Dielectrics
Artificial dielectrics are nano-structured composite materialswhich
can be engineered to possess unique properties in reflectivity,
emissivity, specularity, static and electrically controlled
birefringence, and optical non-linearity.
Diffractive Optical Elements:
Multistage Interconnection
Networks
Design and implementation of an optical MIN using a novel
folded dilated bypass-exchange switch (DBS) based on BCGH
elements.
Birefringent Computer
Generated Holograms
BCGH are general purpose polarization selective optical
elements which have independent, while almost arbitrary,
impulse responses for the two orthogonal polarizations.
Electrooptic Device
Modeling
Modeling, design and fabrication of free-space phase modulators
and polarization rotators based on electrooptic ceramics
with scattering and depolarization characteristics.
Phased-Array
Beam Scanning
Efficient coherent laser beam scanning can be acheived using
a phased array of electrooptic modulators.
Advanced Imaging: Retinal Imaging
Aberrations due to the optics of the human eye limit the
resolution of retinal imaging techniques. We use a deformable
mirror and Hartmann wavefront sensor to provide real-time
aberration compensation. Chromatic Confocal Microscopy
The use of slit and chromatic scanning allows for real-time
and high-resolution 2D mappings of surface profiles.
Photonic Network
Security
Investigation of quantum crypotgraphic protocols as well
as frequency division multiplexing techniques for implementation
of photonic security systems.
