Decrease of pulse-contrast in nonlinear chirped-pulse amplification systems due to high-frequency spectral phase ripples.
It is analytically shown that weak initial spectral phase modulations cause a pulse-contrast degradation at the output of nonlinear chirped-pulse amplification systems. The Kerr-nonlinearity causes an energy-transfer from the main pulse to side-pulses during nonlinear amplification. The relative intensities of these side-pulses can be described in terms of Bessel-functions. It is shown that the intensities of the pulses are dependent on the magnitude of the accumulated nonlinear phase-shift (i.e., the B-integral), the depth and period of the initial spectral phase-modulation and the slope of the linear stretching chirp. The results are applicable to any type of laser amplifier that is based on the technique of chirped-pulse amplification. The analytical results presented in this paper are of particular importance for high peak-power laser applications requiring high pulse-contrasts, e.g. high field physics.
Institute of Applied Physics, Friedrich Schiller University Jena, Albert-Einstein-Str. 15, D-07745 Jena, Germany. damian.schimpf@uni-jena.de
Damian
D
Schimpf
Enrico
E
Seise
Jens
J
Limpert
Andreas
A
Tünnermann
D000669:Amplifiers, Electronic; D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007834:Lasers; D008027:Light; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D055095:Optics and Photonics / Q000295:instrumentation*; D012542:Scattering, Radiation; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*