Fig. 1. Schematic of the experimental setup. SF, spectral filter; PBS, polarizing beam splitter; gratings and G-T mirrors comprise the VDC, which is shown in the dotted frame. The two output beams are measured to analyze compression result with the grating pair only and VDC.

Fig. 2. Numerical simulation results of spectral bandwidth and pulse duration evolution in the laser cavity; the pulse enters the SMF-B after the spectral filter (SF).

Fig. 3. Numerical simulation results. (a) Numerical simulation results of spectral bandwidth (blue circle), dechirped pulse duration (red triangle) and direct output pulse energy (black square). Points A–F represent the different AB-ratios 0.5/0, 0.4/0.1, 0.3/0.2, 0.2/0.3, 0.1/0.4 and 0/0.5, respectively. (b) Autocorrelation trace of the transform-limited pulse of AB-ratio, A (black curve), D (blue curve) and F (red curve). (c) The output maximum and minimum average power of single-pulse operation versus different bandwidths of SF is shown, when AB-ratio is zero. (d) The maximum accumulated in the cavity of single-pulse operation versus different bandwidths of spectral filter is shown, when AB-ratio is zero.

Fig. 4. Experimental results. (a) Output average power (black square) and dechirped pulse duration (red triangle) versus pump power. (b) Pulse train, 50 ns/div, detected by photodiode (200 ps rising time) and analog oscilloscope (400 MHz bandwidth). Inset: two consecutive pulses, 2 ns/div, detected by photodiode (35 ps rising time) and oscilloscope (20 GHz bandwidth). (c) Autocorrelation trace of direct output pulse in a long scan range. Inset: autocorrelation of pulse dechirped by gratings (black solid curve) and transform-limited pulse. (d) Output spectrum when AB-ratio is 0 (black solid curve) and 0.32 (red dotted curve).

Fig. 5. Autocorrelation trace of pulse dechirped by different bounce number of VDC. Inset: details on root of dechirped pulses.