Optical Force and Torque on a Graphene-Coated Gold Nanosphere by a Vector Bessel Beam

Bing Yan; Xiulan Ling; Renxian Li; Jianyong Zhang; Chenhua Liu

doi:10.3390/mi13030456

Optical Force and Torque on a Graphene-Coated Gold Nanosphere by a Vector Bessel Beam

Micromachines (Basel). 2022 Mar 17;13(3):456. doi: 10.3390/mi13030456.

Authors

Bing Yan¹, Xiulan Ling¹, Renxian Li², Jianyong Zhang³, Chenhua Liu⁴

Affiliations

¹ Shool of Information and Communication Engineering, North University of China, Taiyuan 030051, China.
² School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China.
³ School of Computing, Engineering and Digital Technologies, Teesside University, Middlesbrough TS1 3BA, UK.
⁴ Application Science Institute, Taiyuan University of Science and Technology, Taiyuan 030024, China.

Abstract

In the framework of the generalized Lorenz-Mie theory (GLMT), the optical force and torque on a graphene-coated gold nanosphere by a vector Bessel beam are investigated. The core of the particle is gold, whose dielectric function is given by the Drude-Sommerfeld model, and the coating is multilayer graphene with layer number N, whose dielectric function is described by the Lorentz-Drude model. The axial optical force Fz and torque Tz are numerically analyzed, and the effects of the layer number N, wavelength λ, and beam parameters (half-cone angle α0, polarization, and order l) are mainly discussed. Numerical results show that the optical force and torque peaks can be adjusted by increasing the thickness of the graphene coating, and can not be adjusted by changing α0 and l. However, α0 and l can change the magnitude of the optical force and torque. The numerical results have potential applications involving the trapped graphene-coated gold nanosphere.

Keywords: generalized Lorenz–Mie theory; graphene-coated gold nanosphere; optical force; optical torque; polarization; vector Bessel beam.