  A nanostructured target is proposed to enhance an intense-laser contrast:
when a laser prepulse irradiates a nanostructured solid target surface, the
prepulse is absorbed effectively by the nanostructured surface. The
nanostructure size should be less than the laser wavelength. After the prepulse
absorption, the front part of the main pulse destroys the microstructure and
makes the surface a flat plasma mirror. The body of the main pulse is reflected
almost perfectly. Compared with conventional plasma mirrors, the nanostructured
surface is effective for the absorption of the intense laser prepulse, whose
intensity is higher than 10^14 W/cm2. The nanostructured laser cleaner improves
the laser pulse contrast by about a hundredfold. The nanostructured laser
cleaner works well for next-generation intense lasers.
