Physicists at MIT and Livermore
National Lab have discovered a new source of coherent radiation
distinct from traditional lasers and free-electron lasers; they
propose to build a device in which coherent photons are produced by
sending shock waves through a crystal. The result would be coherent
light resembling the radiation issuing from a laser; but the
mechanism of light production would not be stimulated emission, as
it is in a laser, but rather the concerted motion of row after row
of atoms in the target crystal.
The passing shock front, set in
motion by a projectile or laser blast, successively excites a huge
density wave in the crystal; the atoms, returning to their original
places in the matrix, emit light coherently, mostly in the Terahertz
wavelength band. Although sources of coherent light in this part of
the electromagnetic spectrum have developed in recent years, it is
still a difficult task.
The next step will be to carry out an
experimental test of the shock-wave light production. This work
will be performed at two national labs -- Livermore and Los Alamos.
According to Evan Reed (who moved from MIT to Livermore,
email@example.com) the first likely application of coherent radiation
will be as a diagnostic for understanding shock waves. The
radiation should provide information about shock speed and the
degree of crystallinity.
Reed et al.,
Physical Review Letters, 13 January 2006