  We propose a laser-controlled plasma shutter technique to generate sharp
laser pulses using a process analogous to electromagnetically-induced
transparency in atoms. The shutter is controlled by a laser with moderately
strong intensity, which induces a transparency window below the cutoff
frequency, and hence enables propagation of a low frequency laser pulse.
Numerical simulations demonstrate it is possible to generate a sharp pulse
wavefront (sub-ps) using two broad pulses in high density plasma. The technique
can work in a regime that is not accessible by plasma mirrors when the pulse
pedestals are stronger than the ionization intensity.
