Fig. 1. Schematic of the MOPA system

Fig. 2. Closed loop control system of seed laser

Fig. 3. Seed laser linewidth measurement

Fig. 4. A typical 309 ns Gaussian pulse with AOM modulation signal (the inset)

Fig. 5. Schematic diagram of longitudinal gradient strain distribution on gain fiber

Fig. 6. Output power vs pump current

Fig. 7. Optical spectrum of the output pulse

Fig. 8. Physical drawing of laser