At the Jefferson Laboratory (JLab) in Virginia, US, a
multilaboratory team using beams of relativistic electrons has
generated broadband terahertz radiation at nearly 20 W average
power, several orders of magnitude higher than any other source.
The terahertz band - at the far-infrared interface between
electronics and photonics - has drawn increasing attention in
the past decade, despite the lack of high-average-power sources.
The team reported its demonstration of high power in the 14
November edition of Nature.  The terahertz work is a spin-off
from the superconducting radiofrequency (SRF) electron
accelerator central to JLab's mission of probing the quark
structure of nuclei (CERN Courier May 2002). In a news
commentary accompanying the Nature report, Mark Sherwin of the
Center for Terahertz Science and Technology at the University of
California, Santa Barbara, wrote that the high-power
demonstration has "opened the door to new investigations and
applications in a wide range of disciplines".  Terahertz ima