FDTD simulation of trapping nanowires with linearly polarized and radially polarized optical tweezers

Abstract

In this paper a model of the trapping force on nanowires is built by three dimensional finite-difference time-domain (FDTD) and Maxwell stress tensor methods, and the tightly focused laser beam is expressed by spherical vector wave functions (VSWFs). The trapping capacities on nanoscale-diameter nanowires are discussed in terms of a strongly focused linearly polarized beam and radially polarized beam. Simulation results demonstrate that the radially polarized beam has higher trapping efficiency on nanowires with higher refractive indices than linearly polarized beam.

On the electromagnetic scattering of arbitrary shaped beams by arbitrary shaped particles: A review

“…This technique is akin to the classical finite difference schemes used in fluid mechanics for many decades to compute fluid fields. FDTD was used by Li and Wu to simulate trapping of nanowires by linearly polarized and radially polarized optical tweezers [203].…”

Latest achievements in generalized Lorenz‐Mie theories: A commented reference database

“…Jia and Thomas dealt with the radiation forces on dielectric and absorbing particles illuminated by a plane wave, and also with optical forces and optical torques on various materials arising from optical lattices in the Lorenz‐Mie regime. Li and Wu carried out a simulation of trapping nanowires with linearly polarized and radially polarized optical tweezers, in which a fifth‐order Gaussian beam in Davis description was used and special BSCs taken from GLMT were incorporated in the description of the beam in terms of VSWFs (this is an interesting example of the use of GLMT‐ingredients in a non‐GLMT‐framework). Coe and Seibel dealt with improved near‐field calculations using vectorial diffraction integrals in the finite‐difference time‐domain method.…”

Controllable Trapping of Nanowires Using a Symmetric Slot Waveguide

“…Equation gives the electric and the magnetic fields over the boundary of the nanowire that is used to calculate the time-averaged optical force acting on it. Such radiation force is calculated by integrating Maxwell stress tensor over the whole surface of the nanowire: boldF = ⟨ ∮ normald italicl ′ [ ε 1 false( boldE · boldn false) E − ε 1 / 2 | E | 2 n + μ 0 false( boldH · boldn false) H − μ 0 / 2 | H | 2 n ] ⟩ where the bracket represents the time average and n is the outwardly directed unit normal vector. We numerically solve eq for incident SPP waves, each with power of P = (1/2)∫ –∞ ∞ |Re⟨ E × H *⟩|dy per unit length, by using boundary element method and by applying appropriate boundary conditions and considering n i ′ = − n i ′ ( i = 2, 3, 4).…”