COMPRESSIBLE FREQUENCY CHIRPING DUE TO SLOW AND FAST SELF-PHASE MODULATION OF ULTRASHORT PULSES IN HIGH-GRAIN DYE-LASER AMPLIFIERS

We have theoretically investigated amplitude and phase changes in high-gain ultrashort pulse dye laser amplifiers for cases when the beam area is rather small and the pulse spectral center is not located at the amplifier gain peak. Due to high energy densities as well as high intensities, both "slow" (saturation-induced) and fast (Kerr-type) self-phase modulation can take place. Under certain conditions, these effects can together produce a considerable amount of mostly linear carrier chirp, resulting in compressible bandwidth enhancement. Compression of the amplified pulses is also calculated using quadratic as well as quadratic-plus-cubic phase compensation.