Chirped-pulse amplification (CPA) technique has been widely used to generate ultra-intense femto-second pulses. In this scheme the seed pulses from an oscillator are stretched before amplification. The stretched pulses can support more energy extraction and effectively decrease the nonlinear effects in the gain media. The subsequent amplification in a CPA chain will result in a broadening of the output compressed pulses in temporal domain due to the gain narrowing and uncompensated phase distortions. In our experiment, Using spectral modulation and phase pre-compensation system (Acoustic-Optics Programmable Dispersive Filter) between the oscillator and the stretcher, the effects of gain narrowing and high-order dispersions on the pulse duration in kHz chirped-pulse amplification system have been pre-compensated, and the spectral FWHM is expanded from 30nm to 50nm .The effects of GDD, TOD and FOD were investigated by scanning the four dispersion parameters respectively. By pre-compensating the high-order phase distortions with the phase measured by SPIDER, we successfully optimize the output duration from 51fs to 30fs, which is 1.07 times Fourier-transform-limitation.
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