Patent ID: 8730568

Claim:
A method for amplifying laser pulses, comprising: operating an input optical amplifier to amplify input laser pulses to produce laser pulses that have a linear chirp in frequency and are stretched to have a pulse duration longer than a pulse duration of each input laser pulse; operating an optical pulse stretcher down stream from the initial optical amplifier to further stretch durations of the laser pulses to produce stretched laser pulses that have a reduced peak power in each laser pulse; directing the stretched laser pulses into an optical amplifier to amplify the stretched laser pulses to produce amplified stretched laser pulses; compressing a pulse duration of each of amplified stretched laser pulses to produce amplified and compressed output laser pulses with a high peak power; operating an optical pre-amplifier located between the optical pulse stretcher and the optical amplifier to amplify each stretched laser pulse output by the optical pulse stretcher prior to amplification by the optical amplifier; before directing laser pulses output by the pre optical amplifier into the optical amplifier, reducing a pulse repetition rate of the laser pulses; and maintaining the reduced pulse repetition rate higher than a threshold pulse repetition rate to reduce an instability in the optical amplifier or to reduce amplified spontaneous emission in the optical amplifier.