RESUMO
This study proposes a method of dynamically controlling the interference pattern of surface plasmon polaritons (SPPs) within a four-slit structure by changing the phase difference between multiple-incident Gaussian beams. The theoretical analysis of the controlling mechanism of the SPP interference field and the numerical simulation of the generation and movement of both one-dimensional and two-dimensional SPP interference fields are provided. In addition, through simulation, this study demonstrates using the controllable two-dimensional SPP interference bright spots field for manipulating particles in static liquids.
RESUMO
This study proposes a method to achieve excitation of surface plasmon polaritons (SPPs) with tunable directions and intensity ratios on a designed two thin slit structure by the phase control of dual fundamental Gaussian beams. Simply modulating the phase difference between two incident fundamental Gaussian beams (i.e. TEM0,0 mode laser beam) controls the propagating direction of the resulting SPP wave between two opposite linear directions and also the value of the intensity ratio between propagating SPP waves in two opposite directions. The proposed method achieves a wide dynamic SPP intensity ratio adjusting range from -20 dB to 20 dB. This easy method of changing the direction of SPPs makes the dynamic control of the direction of SPP waves practicable, which shows great potential in plasmonic applications.
RESUMO
Chu et al. constructed a kind of Ince-Gaussian modes (IGM)-based vortex array laser beams consisting of p x p embedded optical vortexes from Ince-Gaussian modes, IG(e)(p,p) modes [Opt. Express 16, 19934 (2008)]. Such an IGM-based vortex array laser beams maintains its vortex array profile during both propagation and focusing, and is applicable to optical tweezers. This study uses the discrete dipole approximation (DDA) method to study the properties of the IGM-based vortex array laser tweezers while it traps dielectric particles. This study calculates the resultant force exerted on the spherical dielectric particles of different sizes situated at the IGM-based vortex array laser beam waist. Numerical results show that the number of trapping spots of a structure light (i.e. IGM-based vortex laser beam), is depended on the relation between the trapped particle size and the structure light beam size. While the trapped particle is small comparing to the beam size of the IGM-based vortex array laser beams, the IGM-based vortex array laser beams tweezers are suitable for multiple traps. Conversely, the tweezers is suitable for single traps. The results of this study is useful to the future development of the vortex array laser tweezers applications.
