B-integral compensation in chirped pulse amplification

A method for chirped pulse amplification, comprising steps of:

• stretching laser pulses from an initial ultrashort duration to a longer duration;
• setting a pulse repetition rate of the laser pulses delivered to one or more nonlinear laser amplifiers;
• amplifying the laser pulses in the one or more nonlinear laser amplifiers, an absolute value of a B-integral imposed on the laser pulses by each nonlinear laser amplifier being an increasing function of a respective pump power and a decreasing function of the pulse repetition rate;
• after the stretching and amplifying steps, compressing the laser pulses to a final ultrashort duration by imposing a chromatic dispersion on the laser pulses, a final spectrotemporal characteristic of the laser pulses after said compressing being sensitive to a total B-integral imposed by the one or more nonlinear laser amplifiers;
• and
• changing the pulse repetition rate from a first pulse repetition rate to a second pulse repetition rate;
• and
• for at least one of the one or more nonlinear laser amplifiers, adjusting the respective pump power from a first pump power at the first pulse repetition rate to a second pump power at the second pulse repetition rate, wherein the first and second pump powers, for each nonlinear laser amplifier subject to said adjusting, are selected to maintain the final spectrotemporal characteristic at the first and second pulse repetition rates while the chromatic dispersion imposed in the compressing step is the same at the first and second pulse repetition rates;
• wherein (a) the second pulse repetition rate and second pump power exceed the first pulse repetition rate and first pump power, respectively, or (b) the first pulse repetition rate and first pump power exceed the second pulse repetition rate and second pump power, respectively.