Fig. 1. Schematic of experimental setup. Inset (a) shows spectrum of pulse from seed source (solid line) and reflection spectrum of CFBG (dash line), and inset (b) shows spot pattern distribution when output power after compression is 24 W

Fig. 2. Spectra before main amplifier at different positions. (a) Spectrum of seed source and spectra after filter, CFBG, and pre-amplifier; (b) spectra in main amplification process at different output powers

Fig. 3. Group delay and net group delay curves of CFBG and grating pair

Fig. 4. Experimental results at output power of 27 W. (a) AC curves of pulses; (b) pulse profiles retrieved by PICASO algorithm