Schimpf Damian, Seise Enrico, Limpert Jens, Tünnermann Andreas
Institute of Applied Physics, Friedrich Schiller University Jena, Albert-Einstein-Str. 15, D-07745 Jena, Germany.
Opt Express. 2008 Jun 9;16(12):8876-86. doi: 10.1364/oe.16.008876.
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.
分析表明，弱的初始光谱相位调制会导致非线性啁啾脉冲放大系统输出端的脉冲对比度下降。克尔非线性在非线性放大过程中会导致能量从主脉冲转移到边脉冲。这些边脉冲的相对强度可用贝塞尔函数来描述。结果表明，脉冲强度取决于累积非线性相移的大小（即B积分）、初始光谱相位调制的深度和周期以及线性拉伸啁啾的斜率。这些结果适用于基于啁啾脉冲放大技术的任何类型的激光放大器。本文给出的分析结果对于需要高脉冲对比度的高峰值功率激光应用，如高场物理，尤为重要。
