Fig. 1. Schematic diagram of underwater fiber laser propulsion

Fig. 2. Input/output model of numerical simulation

Fig. 3. Change curves of thrust and impulse coupling coefficient of microsphere particles at different focus positions. (a) Thrust curve; (b) impulse coupling coefficient change

Fig. 4. 0.2 μs flow field

Fig. 5. Schematic diagram of laser propulsion in short microcavity structure

Fig. 6. Detonation wave pressure flow field of microcavity structures with different length at 0.5 μs. (a) 60 μm; (b) 75 μm; (c) 90 μm; (d) 100 μm

Fig. 7. Thrust curves and impulse coupling coefficients under different microcavity lengths. (a) Thrust curves; (b) impulse coupling coefficient

Fig. 8. Cloud images of pressure flow field of microspheres with different cavity diameters at 0.5 μs. (a) 20 μm; (b) 30 μm; (c) 40 μm

Fig. 9. Efficiency parameters of laser propulsion under different microcavity diameters. (a) Thrust curves; (b) impulse coupling coefficient

Fig. 10. Schematic diagram of U-shaped microcavity structure propulsion

Fig. 11. Pressure flow field diagrams of U-shaped microcavity structure at different time. (a) 0.1 μs; (b) 0.3 μs; (c) 0.5 μs; (d) 0.8 μs

Fig. 12. Stress curves of microsphere particles in U-shaped and rectangular microcavity structures

Fig. 13. Detonation wave pressure flow field under double-tube microcavity at different time. (a) 0.1 μs; (b) 0.3 μs; (c) 0.5 μs; (d) 0.8 μs

Fig. 14. Thrust curves of microsphere particles for single- and double-tube microcavities

Fig. 15. Schematic diagram of microcavity blocking structure

Fig. 16. Cloud images of detonation wave pressure flow field with blocking structure at different time. (a) 0.1 μs; (b) 0.3 μs; (c) 0.5 μs; (d) 0.8 μs

Fig. 17. Thrust curves of microsphere particle for blocking structure and non-blocking structure