Fig. 1. Optical spring diagram

Fig. 2. Scattering force and gradient force of off-axis high index microsphere in the near-field of a mildly focused Gaussian beam^[31]

Fig. 3. Normalized PSD of the microsphere moving along the propagation direction of the trapped beam under different pressures. The three curves represent underdamped, critically damped and overdamped statuses respectively^[35]

Fig. 4. General layout diagram

Fig. 5. Schematic diagram of load-lock technology^[43]

Fig. 6. Vibration diagram of piezoelectric transducer^[47]

Fig. 7. Transport diagram of HC-PCF^[50]

Fig. 8. Microsphere optical trap apparatus diagram^[26]

Fig. 9. Schematic diagram of typical optical trap. (a) Upward single-beam trap; (b) counter-propagating horizontal double-beam trap

Fig. 10. Schematic diagram of forward detection and backward detection^[81]

Fig. 11. Schematic diagram of microsphere detection module of Rider’s team^[6]

Fig. 12. Schematic diagram of position detection module of Moore’s team^[92]

Fig. 13. Schematic diagrams of feedback cooling. (a) Optical momentum feedback cooling^[24]; (b) prameter feedback cooling^[19]; (c) electrostatic force feedback cooling^[99]; (d) optical cavity feedback cooling^[21]