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Grad student most outstanding at Latvia conference

A Lehigh graduate student whose research has potential application to all-optical electronic devices has received the outstanding oral presentation award at the 15th International Conference on Defects in Insulating Materials (ICDIM 2004).

Christian Sandmann, a Ph.D. candidate in physics, was honored for his talk on “The role of defects in light-induced poling.” He was the only graduate student chosen for an oral presentation award from a large group of young scientists.

The week-long conference, held in July in Riga, Latvia, was sponsored by the Institute of Solid-State Physics of the University of Latvia and the Institute of Physics at the University of Tartu in Estonia.

Sandmann’s trip to the conference was sponsored by Lehigh’s Center for Optical Technologies and also by the European Union Sixth Framework Program Marie Curie Large Conferences Action. The Framework Program is the EU’s main instrument for research funding in Europe.

Sandmann studies with Volkmar Dierolf, associate professor of physics, who is working toward understanding and developing integrated optical devices in lithium niobate, a crystalline dielectric material noted for its electro-optical, acousto-optical and nonlinear optical properties.

Devices with nonlinear properties are valued because of their ability to create light waves of varying wavelengths, including those in the infrared and mid-infrared ranges.

Sandmann uses optical spectroscopy to investigate non-linear LiNbO3-based waveguide devices.

In his talk in Riga, Sandmann presented two breakthrough findings that he and Dierolf have achieved – how to switch the ferroelectric polarization vector of LiNbO3 using light, and how to create patterns of differently oriented vectors in the micro scale.

“Using our technique,” says Sandmann, “you can ‘write’ these switching patterns with light.”

Sandmann, who has completed undergraduate and graduate studies at the University of Paderborn in Germany, has published a dozen articles, many of them co-authored with Dierolf, in Applied Physics Letters, the Journal of Applied Physics, the Journal of Luminescence and other journals. He has presented papers at conferences in Budapest, Montreal, Munich, Prague and San Francisco, in addition to the ICDIM conference in Latvia.

Sandmann and Dierolf’s work with light-induced ferroelectric domain switching was featured in the July issue of Laser Focus World in an article titled “Ferroelectric domain patterns are directly written into lithium niobate.”

In August, Sandmann and Dierolf wrote an invited feature article titled “Laser Writes Ferroelectric Domains in a Confocal Microscope” for the journal Photonics Spectra. In this article, they discussed their use of confocal microscopes, combined with Raman spectroscopy, to produce the electric space-charge fields that induce the domain inversion in ferroelectric LiNbO3.

Their technique, says Dierolf, “has the potential to replace time-consuming and expensive photo-lithographical methods in production of nonlinear frequency conversion devices such as frequency doubled lasers and all-optical switches.”

Sandmann and Dierolf are members of the Center for Optical Technologies.

--Kurt Pfitzer

Posted on Wednesday, September 22, 2004

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