Fig. 1. Schematic diagram of experimental setup for high-power all fiber structure picosecond pulse thulium doped fiber laser. (a) Oscillator; (b) First stage amplifier; (c) Second stage amplifier; (d) Third stage amplifier

Fig. 2. (a) Oscillator spectrum; (b) Oscillator pulse sequence；(c) Output pulse width of oscillator；（d） Oscillator frequency spectrum

Fig. 3. (a) Main amplifier output spectrum; (b) Main amplifier pulse width；(c) Amplifier slope efficiency

Fig. 4. Laser lithotripsy optical path setting

Fig. 5. (a) Stone mass loss at different laser power settings during 120 s; (b) Loss of stone quality with different spot diameters within 120 seconds of action time

Fig. 6. The relationship between the stone mass loss and the action time under different laser power in 180 s

Fig. 7. (a) The effect of laser power on the temperature of the liquid around the stone during 120 s; (b) The influence of spot diameter on the temperature of the liquid surrounding the stone

Fig. 8. The effect of laser action time on the temperature of the liquid around the stones within 180 s

Fig. 9. Analysis of stone morphology. (a) Optical microscope image of crushed stone; (b) Optical image of crushed stone debris; (c) SEM image of crushed stone; (d) Enlarge the area

Fig. 10. Fourier transform infrared spectroscopy product analysis. (a) Before the interaction between laser and stones; (b) After the interaction between laser and stones