A frequency-drift amplification device for a pulsed laser, including: a stretcher for time-stretching an incident laser pulse; at least one amplifying medium for amplifying the laser pulse; a main compressor for time-compressing the laser pulse to a desired duration for an output pulse of the amplification device; and at least one adjustment compressor between the stretcher and the main compressor, and in which the laser pulse undergoes four diffractions on diffraction gratings to time-compress the stretched laser pulse to a duration that is greater than the desired duration for the output pulse of the amplification device.