Shock-Produced Coherent Light

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, reed23@llnl.gov) 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