Fig. 1. Structure of this paper

Fig. 2. Schematic of absorbing and scattering optical torques in circularly polarized light. (a)(b) Two different generation mechanisms of optical torque mediated by absorption and scattering, respectively^[37]; (c) generation mechanism of negative optical torque

Fig. 3. Schematic of optical torque from OAM^[58]

Fig. 4. Optical torque from the SAM-OAM^[48]. (a) SAM-OAM interaction generated by conical wavevector distribution through tight focusing of a paraxial wave; (b)SAM-OAM interaction generated by particle scattering; (c) SAM-OAM interaction generated by wave propagation in evanescent field

Fig. 5. Examples of planar structures that can realize negative optical torque^[63]. (a)-(g) Different structures composed of an array of identical dielectric spheres^[63]; (h) the incident plane wave has a k-vector (k) along the z-axis

Fig. 6. Particle kinetics by the optical force (arrow) and optical torque (ring)^[78]

Fig. 7. Negative optical torque on a birefringent particle by the transferring of the linear momenta^[80]. (a) Diagram of the optical setup; (b) SEM image of a nano-fabricated birefringent quartz cylinder with OTW; (c) schematic depicting of the torque generation inside a birefringent crystal

Fig. 8. Negative optical torque on plasmonic chiral particles^[44]. (a) Illustration of the nano-sized gold motor; (b) SEM image of a silica disk including the plasmonic motor; (c) electric field and Poynting vector induced on the motor at an illumination wavelength of λ = 810 nm; (d) electric field and Poynting vector induced on the motor at an illumination wavelength of λ = 1700 nm

Fig. 9. Spin torque from the SAM-OAM coupling at an interface excited by a circularly polarized light^[95]

Fig. 10. Enhancing the optical torque by the ring resonator^[43]

Fig. 11. Enhancing optical torques by different plasmonic structures. (a) Chiral particles^[44]; (b) triangular and rectangular particles^[37]; (c) nanorod^[96-97]; (d) V-shape particle^[98]

Fig. 12. Enhancing positive and negative optical torques by superhybrid modes from the combination of the electric toroidal dipole and magnetic multipoles^[47]. (a) Schematics of optical torque on the triangular prism with side a and thickness t (clockwise rotation corresponds to the positive optical torque); (b) illustration of three hybrid modes induced in the prism (red lines represent electric displacement current, green lines represent magnetic flux)

Fig. 13. Setup of the OTW^[112]

Fig. 14. Examples of micromechanics. (a) Rotation of the gold nanorod by a circularly polarized light^[130,135]; (b) illustration of the Archimedes micro-screw^[135]; (c) rotating the liquid by two particles with opposite optical torques in the microchannel^[136]

Fig. 15. Schematic of the setup for twisting DNA^[118]

Fig. 16. Controllable rotation of CR^[142]. (a) Without the scanning trap, the CR rotated counterclockwise; (b) with the scanning trap applied (75 mW), the rotation is reversed to clockwise; (c) as the power of the scanning trap is increased (ii and iii: 95 mW, iv and v: 110 mW), the clockwise rotation speed increased