Dispersion-free amplification of femtosecond dye-laser pulses.

Amplification of femtosecond pulses through spatial expansion and recompression in a temporally nondispersive grating apparatus is demonstrated. The system used does not lengthen the pulse, provides higher gain than conventional amplifiers, and separates effectively the amplified spontaneous emission from the signal. The output pulse duration is easily controlled from tau(min) = 50 fs to several hundred femtoseconds by fine adjustment of the components used in the spatially dispersive scheme.