2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009;
Denver, Colorado
Session R6: Imaging Advanced Accelerators
1:30 PM–3:18 PM,
Monday, May 4, 2009
Room: Governor's Square 16
Sponsoring
Units:
DPP DPB
Chair: Thomas Antonsen, University of Maryland
Abstract ID: BAPS.2009.APR.R6.2
Abstract: R6.00002 : Ultrafast terahertz generation and spectroscopy for accelerator diagnostics
2:06 PM–2:42 PM
Preview Abstract
Abstract
Author:
Ki-Yong Kim
(University of Maryland)
The generation of strong terahertz (THz) radiation has recently
drawn
considerable attention owing to the potential for intense THz
excitation
spectroscopy, nonlinear THz optics, as well as biomedical and
security
imaging. For these applications, THz field strength of MV/cm (or
several
microjoule under single-cycle, diffraction-limited focusing) is
required.
Such field strength can be obtained currently at electron
accelerator
facilities such as linacs, synchrotrons, and free electron
lasers, as well
as at laser-plasma accelerators, where all mediate highly
relativistic
electrons. Surprisingly, non-relativistic electrons can also
generate
intense coherent THz radiation. Recently, high-energy ($>$5
microjoule),
super-broadband ($>$75 THz) THz radiation has been produced via
ultrafast
two-color photoionization [1]. In this scheme, a femtosecond laser's
fundamental and its second harmonic pulses are mixed in a gas to
generate a
directional electron current on the time scale of sub-50 fs with
simultaneous THz radiation in the far field. Another important THz
application is diagnosing the temporal profiles of relativistic
electron
beams. As a noninvasive method, the longitudinal profile can be
characterized from field-induced birefringence in an
electro-optic crystal
in the vicinity of the electron beam. To monitor the bunch
profiles in real
time, a chirped optical pulse can be used to map out the charge
field onto
the probe spectrum. Here, the temporal resolution, previously
limited by the
chirp, can be greatly improved with an in-line spectral
interferometric
algorithm [2]. The diagnostic can also provide 2D spatio-temporal
imaging of
ultrashort electron bunches in real time. Another single-shot
diagnostic
recently developed is an echelon-assisted spatial encoding method
[3] which
can provide a $>$10 ps time window with $\sim $25 fs temporal
step sizes,
with many advantages over other single-shot THz diagnostics.
\\[4pt]
[1] K. Y. Kim \textit{et al}., Nature Photon. \textbf{2}, 605
(2008)\\[0pt]
[2] K. Y. Kim \textit{et al}.,
Appl. Phys. Lett. \textbf{88}, 041123 (2006)\\[0pt]
[3] K. Y. Kim \textit{et al}., Opt. Lett. \textbf{32}, 1968 (2007).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.APR.R6.2