NORTH CAROLINA STATE UNIVERSITY
DEPARTMENT OF PHYSICS
Optics
Overview
The optics group at North Carolina State University
investigates a broad range of topics from X-rays to
millimeter waves, nanoscale to the upper atmosphere,
and the fundamental interactions of light and matter to
applied optics. Some pioneering advances by the optics
group include testing the first blue laser diode fabricated
in America, building the most frequently copied X-ray
microscope,
inventing
reflectance
difference
spectroscopy, producing the first nano-Raman images,
and developing Raman lidar. Several recent projects
include X-ray microscopy, nonlinear optics, solar cell
studies, materials growth monitoring, ultrafast optics and
wavelength diversity, resonance Raman scattering,
optimizing lidar for temporal and spatial resolution,
near-field techniques, and fluorescence imaging.
Faculty Members and Research Interests
Harald Ade
Prof. Ade’s group uses the scanning transmission X-ray
microscope at the Advanced Light Source in Berkeley.
It was built by a team led by the Ade group and has the
distinction of being the most frequently copied X-ray
microscope. Significant research efforts are directed in
the area of resonant soft X-ray scattering, which is the
small angle X-ray scattering equivalent near an
absorption edge such as C, N, or O. It provides vastly
improved capabilities for soft matter characterization. By
tuning the photon energy, the reflection from the top
surface of a polymer bilayer can be “turned off” and the
structure of the buried interface can be studied.
Knowledge about the complex index of refraction and
how it impacts scattering is important for data
interpretation. (harald_ade@ncsu.edu)
Dave Aspnes
Research in Prof. Aspnes’ group consists of a mix of
theory and experiment. The laboratory is equipped with
several spectroscopic ellipsometers, one operating in the
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vacuum ultraviolet, one in the standard quartz-optics
range, and one integrated into an organometallic
chemical vapor deposition (OMCVD) system. The
OMCVD system also allows the study of epitaxial
growth of materials systems and is unique in this regard.
There is also a laser system for performing nonlinearoptical experiments. The theory component is directed
towards a better understanding of the interaction of light
with material, and solving continuing outstanding
problems of optics. Recent theoretical work includes the
anisotropic bond model of nonlinear optics, which
provides a simple physical interpretation of nonlinearoptical phenomena; optics of nanostructured materials
for materials analysis; and plasmonics, specifically
understanding plasmonic responses of thin conductingoxide films. (david_aspnes@ncsu.edu)
Laura Clarke
Prof. Clarke's research group seeks to apply traditional
optical tools in novel ways for the study of nanoscale
physics and surface science. Fundamentally, light is used
to prepare and control systems, as well as a means to
elegantly elucidate the underlying physics. Some recent
projects include fluorescence anisotropy and dielectric
spectroscopy measurements to deduce the rotational
dynamics of sub-monolayer assemblies of surface-bound
molecules, and fluorescence imaging for optimizing
scaling-up electrospinning approaches. Other recent
work involves utilizing the photothermal effect of metal
nanoparticles doped into materials to act as nanoscale
heaters and simultaneously performing a sensitive,
spectrally-resolved fluorescence technique for real-time,
in-situ
nano-thermometry
measurements.
(laura_clarke@ncsu.edu)
Kenan Gundogdu
Prof. Gundogdu’s research investigates electronic and
structural dynamics in condensed matter systems using
nonlinear optical spectroscopy. His group has developed
coherent and incoherent ultrafast optical experiments to
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study electron/exciton dynamics in the interfaces of
organic/inorganic hybrid structures. Some important
questions include the role of coherent/incoherent exciton
transport in photovoltaic structures, how dynamic and
static disorder affect coherent energy transport, how
energy transport occurs in interfaces involving inorganic
and organic materials, and the nature of excitons in such
hybrid materials.
In addition, nonlinear optical
techniques are used to investigate bond-specific
structural dynamics of interface formation during
semiconductor growth. (kenan_gundogdu@ncsu.edu)
Hans Hallen
Prof. Hallen leads a research group with an emphasis on
optics, particularly spectroscopy, the interaction of
electromagnetic fields near nano-scale conductors, and
scattering by small particles. He also has projects in
modeling
and
measurements
of
wireless
communications channels. He led the group that
produced the first nano-Raman images, and identified
new physics in nanoscale optical spectroscopy. Work
also has investigated on-resonance deep ultraviolet
resonance Raman spectroscopy. This will find
applicability in nano-Raman and trace substance analysis
in lidar, another interest of the group. Topics in lidar
research include multi-wavelength spectroscopy,
scattering by small aerosols as measured by multistatic
lidar,
and
resonance
techniques.
(hans_hallen@ncsu.edu)
Russell Philbrick
Prof. Philbrick’s research focuses on developing laser
remote sensing techniques and investigations using lidar
for studies of the properties and processes of the lower
atmosphere. The primary research has centered on
developing Raman lidar for investigations of
meteorology, air pollution physics, atmospheric effects
on radar refraction, and trace species measurements. Dr.
Philbrick led the EPA sponsored NARSTO-NEOPS
project to investigate processes governing the
development of air pollution episodes. He has also
served as the principal technical advisor for lidar
projects that have been developed by the government for
the detection of hazardous chemicals. Current research
goals are centered on improving the sensitivity of remote
sensing using lidar with wideband sources, multi-static
detection, resonance Raman scattering processes, and
measurements of aerosol properties from scatter of
polarized laser beams. (philbrick@ncsu.edu)
Robert Riehn
Prof. Riehn is interested in the use of optical
technologies in biological analysis. A first direction,
undertaken together with Prof. Hallen, aims at using
resonant near-field optical structure for Raman
spectroscopy of complexes of DNA and proteins. These
complexes are relevant to cancer biology and embryonic
development. A second direction is the integration of
optical methods with lab-on-a-chip analyses. The main
emphasis is the use of optical methods to prepare and
separate chromosomes from whole biological specimens
for biological analysis. Furthermore investigations are
being done to integrate near-field optics with nanofluidic
devices. (rriehn@ncsu.edu)
Keith Weninger
Prof. Weninger develops new optics methodologies for
application to molecular biophysics.
He builds
instruments with the capability to perform optical
spectroscopy and polarization sensitive measurements
on samples as small as single molecules. Near-field
dipole coupling between two fluorescent moieties (a
phenomena known as resonance energy transfer) enables
sensitive spectroscopic measurements to report
nanoscale distances within biological molecules. This
approach allows dynamic motions of these molecules to
be recorded in real time. (keith_weninger@ncsu.edu)
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Further Information
We encourage interested applicants to learn more through the optics group webpage, www.physics.ncsu.edu/optics.
Prospective students can contact any faculty member directly or the Graduate Program office at py-gradprogram@ncsu.edu.
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www.physics.ncsu.edu