Ultrafast smoothing scheme for improving illumination uniformities of laser quads.

The beam smoothing technology, smoothing by spectral dispersion, plays an important role in improving the illumination uniformities of the lasers in inertial confinement fusion facilities. However, due to the limitations of the modulation frequency of the electro-optic modulator, the uniformity of the lasers approaches an asymptotic value after tens of picoseconds that are much longer than the response time of laser plasma instabilities. To the best of our knowledge, this is the first time that an ultrafast smoothing approach for improving the uniformity of a laser quad in both radial and azimuthal directions in the picosecond scale was proposed.

Suppression of progressive growth of intensity modulations with slit spatial filter in a laser system.

The performance of a slit spatial filter composed of two astigmatic lenses and two orthogonal slits for suppressing progressive growth of intensity modulations in a laser system was studied. Power spectral density (PSD) is used to evaluate the beam performance in the frequency domain. The filtering characteristics, image relay, and beam expansion properties of the slit spatial filter are discussed and demonstrated.