Study of nonlinear propagation of chirped optical pulses in laser amplifying medium

In chirped pulse amplification, the amplification of an optical pulse in laser amplifying medium is a very important link. After considering dispersion, Kerr nonlinear effect, gain distribution and loss of the medium, the physical model that the optical pulse propagates in the medium has been established, which is suitable for the general situation where the optical pulse propagates in the amplifying medium. Using a split-step Fourier method, the propagation state of a chirped optical pulse in the amplifying medium has been numerically simulated, and the influences of the gain dispersion of the medium and the frequency detuning of the pulse on the optical pulse have been discussed emphatically. The results show that, with the amplification and propagation of the ultrashort chirped pulse in the amplifying medium, gain saturation and Kerr nonlinear effect of the medium will cause distortion of the optical pulse. For the optical pulse with a wideband spectrum, gain dispersion will cause the gain narrowing effect, so it is equivalent to a loss mechanism. The frequency detuning of the optical pulse will cause distortion of the pulse, which can be used to weaken the impact of gain saturation, thus reshaping the optical pulse.