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. Differences in the Raman spectra in lithium tantalate across a domain wall shown in the inset. 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 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. Raman Imaging of Ferroelectric Domain Walls for Photonic Applications Raman Imaging of Ferroelectric Domain Walls for Photonic Applications Volkmar Dierolf and Venkat Gopalan DMR

Education and Outreach Education and Outreach Volkmar Dierolf and Venkat Gopalan DMR Chad in Bonn setting up a light aided domain inversion experiment. Greg on a visit to MPI for Quantum Optics in Garching 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! 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 Dierolf’s 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.

Additional Slides and Pictures

Education and Outreach Education and Outreach Volkmar Dierolf and Venkat Gopalan DMR NSF-REU students 2 undergraduate students performed summer research in Germany in 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).

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)