Raman Imaging of Ferroelectric Domain Walls for Photonic Applications Volkmar Dierolf and Venkat Gop

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Raman Imaging of Ferroelectric Domain Walls for
Photonic Applications Volkmar Dierolf and Venkat
Gopalan DMR-0349632
For the first time, Raman spectroscopic imaging
has been performed to map structural changes
across a ferroelectric domain wall in the
technologically important materials lithium
niobate and tantalate on the sub-micron length
scale. Raman emission peaks shift their
frequencies and new peaks appear across the
domain wall, indicating changes in vibrational
bond strengths and local symmetry. These
unexpected changes arise from small amounts of
compositional non-stoichiometry.
Shaping ferroelectric domain walls is used to
create a wide range of integrated optical devices
such as optical switches, beam steering prisms,
dynamic focusing lenses, and optical frequency
conversion gratings. This technique will allow
us to track in real time, changes that occur as
ferroelectric domains are shaped in creating
these optical devices.
Parts of this research has been carried out by
two undergraduate students from Lehigh and Penn
State Universities in collaboration with
University of Bonn, where they worked in summer
2005.
Differences in the Raman spectra in lithium
tantalate across a domain wall shown in the inset.
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Education and Outreach Volkmar Dierolf and
Venkat Gopalan DMR-0349632
As part of the collaborative program, Chad
Althouse (Penn State, 2008) and Greg Stone
(Lehigh, 2005) spend one month (June 2005) in
Bonn, Germany. They worked in the labs of Prof.
K. Buse in the Physics department of the
University of Bonn and performed experiments on
different aspects of light aided domain inversion
in ferroelectrics. They spend another 5 weeks at
Lehigh in Dierolfs lab performing spectroscopic
studies on the samples they have prepared in
Bonn. We expect this work to lead to a
publication in the near future.
Chad in Bonn setting up a light aided domain
inversion experiment.
Aside from a busy summer of research, the two
undergraduates had the chance to visit the
biggest laser trade show in Europe (Laser 2005,
Munich) and the Max-Planck Institute for Quantum
Optics in Garching, where they saw an atom
fountain in action. They also found time in their
busy schedule to explore German culture and do
some sightseeing along the beautiful Rhine river.
Both of them would love to return and continue
their exciting experiences!
Greg on a visit to MPI for Quantum Optics in
Garching
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Additional Slides and Pictures
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Education and Outreach Volkmar Dierolf and
Venkat Gopalan DMR-0349632

• 4 NSF-REU students
• 2 undergraduate students performed summer
  research in Germany in 2005.
• Researcher from an undergraduate institution at
  Lehigh
• High school teachers create electro-optics
  lessons at Penn State
• Philadelphia Ladies in Science at Penn State
  Workshop on the science and technology of light.

(Left) Paul Longwell, State College (PA) area
high school physics teacher, creating an
electro-optics experiment with graduate student
Lili Tian at Penn State. (summer 2005) (Below and
right) Dierolf and Gopalan conducting a
workshop on the Science and Technology of Light
for Philadelphia high school students (Fall 2004).
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Opto Camp for female high school students
Prof. Dierolf explaining the basics of near field
optical microscopy to Lehigh valley high school
students (July, 2005)