Temporal contrast improvement for short pulse lasers via ionization gratings

A laser system for producing laser pulses having increased temporal contrast, said laser system comprising:

• a supply configured to provide a medium that can be altered with light;
• at least one laser and optics configured to provide first and second laser beams, each beam comprising a plurality of laser pulses, said laser and said optics arranged such that said first and second laser beams are disposed with respect to each other and with respect to the medium so that individual pulses from said first laser beam interfere with individual pulses from said second laser beam to form an interference pattern on the medium for a limited time to cause said medium to form a transient plasma diffraction grating that persists for at least about 1 ps after the end of the respective pulses from said first laser beam and the second laser beam, said at least one laser and optics configured to provide a third beam comprising a plurality of pulses that pass through the transient plasma diffraction grating such that a portion of said third beam is diffracted by said plasma diffraction grating, individual ones of said laser pulses in said third beam that is incident on said transient plasma diffraction grating comprising a peak accompanied by some light just prior in time to said peak,
• wherein said first and second laser beams each have an optical path distance to the location where said plasma diffraction grating is formed, and said third laser beam has an optical path distance to said location where said plasma diffraction grating is formed to cause the transient formation of said plasma diffraction grating to be delayed in time with respect to said laser pulses in said third beam incident thereon so as to diffract said peak in said laser pulses in said third beam and reduce the amount of said light preceding said peak in the third beam that is diffracted by said transient plasma diffraction grating.