Synthesis of phase-coherent, picosecond optical square pulses.

We report the generation of Fourier-transform-limited, picosecond optical square pulses (with a duration of ~6 psec full width at half-maximum and a rise time of ~1 psec). Control of the pulse temporal profile is achieved by masking the amplitude and the phase of the optical frequency components, which are spatially dispersed within a grating pulse compressor.