Fig. 1. Working principle diagram. (a) Dual-beam optical trap; (b) four-beam optical trap

Fig. 2. Relevant parameters of light incident on the surface of the microsphere

Fig. 3. Geometry of microsphere illuminated by Gaussian beam

Fig. 4. Distribution of light trapping forces on microspheres. (a) Dual-beam optical trap; (b) four-beam optical trap

Fig. 5. Curves of trapping force in the dual-beam optical trap. (a) x direction; (b) z direction; (c) y direction

Fig. 6. Curves of trapping force in the four-beam optical trap. (a) x direction; (b) z direction; (c) y direction

Fig. 7. Trap stiffness versus the input power

Fig. 8. Structure of the chip. (a) Dual-beam optical trap; (b) four-beam optical trap

Fig. 9. Experimental structure of the four-beam optical trap

Fig. 10. Microsphere captured in the four-beam optical trap. (a) Microsphere moves to the capture chamber; (b) microsphere enters the capture chamber; (c) successfully captured

Fig. 11. Varying curves of relative replacement in the dual-beam optical trap. (a) z direction; (b) x direction

Fig. 12. Varying curves of relative replacement in the four-beam optical trap. (a) z direction; (b) x direction

Fig. 13. Optical trap stiffness varies with optical power in the experiment