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Researchers Achieve New Control of Useful Long-Wavelength Radiation
Update: Mandated Harassment Prevention Training

SLAC Today

Tuesday - September 29, 2009

Researchers Achieve New Control of Useful Long-Wavelength Radiation

(Image - diagram of experimental setup)
Using a red laser, mirrors and a beta-barium borate crystal, or BBO, the polarization of an intense terahertz field can be controlled by slightly adjusting timing between pulses of blue and red laser light. (Image courtesy Aaron Lindenberg and Haidan Wen.)

Physicists Aaron Lindenberg and Haidan Wen of the PULSE Institute for Ultrafast Energy Science have discovered a new mechanism for manipulating terahertz radiation fields, which are widely used in materials characterization, chemical sensing and noninvasive imaging. This work provides a new means for controlling the polarization of light at terahertz frequencies and represents a novel tool to help both reveal and direct ultrafast processes in materials. This work was published in Physical Review Letters on July 7.

"Our experiments have implications on both fundamental and applied research," Wen said. First, Wen said, the work helps researchers to understand the physics of generating terahertz radiation, making it possible to create more intense fields. Second, he said, the work provides a means to adjust terahertz polarization, which has not been possible before.

"This new research frontier known as plasma photonics has attracted great attention recently," Wen added. A similar result using a different experimental approach was reported by a research team from the Rensselaer Polytechnic Institute in the same issue of Physical Review Letters.

Terahertz radiation, characterized by long wavelength and low photon energy, lies at the opposite extreme of the electromagnetic spectrum with respect to X-rays. It has been used as a tool for characterizing materials for decades, but until recently scientists have not been able to generate terahertz radiation at intensities high enough to alter material properties.  Read more...

Mandated Harassment Prevention Training

The 2009 mandated harassment prevention training for supervisors and faculty must be completed by December 1. This fall we will continue to offer the option of online or live training.

Both LawRoom's online course and the live training programs have been updated for 2009, and we are fortunate to have Life Theatre Services present live training again this fall. To register, please inform the supervisors in your area to look for periodic e-mail reminders from LawRoom. Course registration is not offered through STARS. The live training sessions have filled up quickly, so sign up soon.

If you have any questions, please contact Virginia Pollard or Robbie Fanning at or 725-0646.

Comments about the training programs:

"The live interaction, the questions and comments, and the realizations people share, IS MUCH BETTER training than a theoretical understanding. Nothing beats actual physical training and "doing" to shape future response, in my opinion."

"This has been the most effective course of this type I have taken. The time element makes it very effective. I was somehow encouraged to be serious about this course instead of just getting through the questions."


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