We present here a detailed study of a compact and tunable nonlinear phase pre-compensation method based on a tunable chirped fiber Bragg grating (TCFBG) applied to an ultrafast fiber laser system. Frequency resolved optical gating (FROG) measurements reveal a significant variation in the output pulse shape due to the variation in accumulated nonlinear phase for varying pulse energy and repetition rate (even if the pulse energy is kept constant) of the laser system. The TCFBG, used as a stretcher and a pre-compensating element in this chirped fiber amplification (CPA) system, eliminates the need for additional pulse shaping components which greatly simplifies the system for tunable pre-compensation. We demonstrate an efficient pre-compensation of the accumulated nonlinear phase between 0 and 14 rad resulting in pulses with a constant pulse duration and Strehl ratio over a broad operating regime of the laser with repetition rates ranging from 100 kHz up to 30 MHz and pulse energies spanning from 1 µJ up to 70 µJ.

在此，我们将对基于可调谐chi光纤布拉格光栅（TCFBG）的紧凑可调谐非线性相位预补偿方法进行详细研究，并将其应用于超快光纤激光系统。频率分辨光学选通（FROG）测量表明，由于激光系统的脉冲能量和重复频率（即使脉冲能量保持恒定）变化，所累积的非线性相位也会发生变化，从而导致输出脉冲形状发生显着变化。TCFBG在此chi光纤放大（CPA）系统中用作担架和预补偿元件，因此无需额外的脉冲整形组件，从而大大简化了用于可调预补偿的系统。