Fig. 1. Experiment on laser pulse emitted from tip propelling microsphere. (a) Schematic diagram of experimental setup; (b)-(d) fiber tips with diameters of about 1.9, 10, and 125 μm, respectively

Fig. 2. Motion process of microsphere propelled by single laser pulse, and energy of pulse coming out from tapered fiber tip is ~9.6 μJ. (a)-(h) Images of moving trace of microsphere, and time interval is 1/1000 s; (i) schematic diagram of relative position of fiber tip and center of microsphere

Fig. 3. Effects of laser energy and microsphere size on microsphere motion. (a) E is ~3.5 μJ and diameter is ~40 μm; (b) E is ~25 μJ and diameter is ~40 μm; (c) E is ~25 μJ and diameter is ~70 μm; (d) image of microsphere motion distance with energies of ~3.5 μJ and ~25 μJ; (e) image of microsphere motion distance with diameters of ~40 μm and ~70 μm; (f) C_m as a function of laser energy

Fig. 4. Plasma formation and fiber tip damage. (a) Production of high-energy electrons; (b) high-energy electrons colliding with atoms; (c) influence of laser energy on fiber tip damage: (i) E=0; (ii) E is ~3.5 μJ; (iii) E is ~8 μJ; (iv) E is~27 μJ

Fig. 5. Measurement of laser energy outgoing from fiber tips with different diameters. (a) Microscope image of fiber tips with diameters changing from 2 to 125 μm. Insert is scanning electron microscope (SEM) image of 2 μm fiber tip, and scale bar is 5 μm; (b) relationship between measured pulse energy and fiber tip diameter; (c) relationship between energy density and fiber tip diameter