P7 – Scattering of Surface Plasmon Polaritons by Gold ... - repetit.dk

Chapter 3
Numerical Results
Contents
3.1 Scalar Model Results . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.1.1 Single Particle Scattering . . . . . . . . . . . . . . . . . . . . . . . . 39
3.1.2 Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.1.3 Waveguides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.2 Vectorial Model Results . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2.1 Scalar Model and Vectorial Model Comparison . . . . . . . . . . . . 42
3.2.2 Parabolic Nanoparticle Chains for SPP Beam Focusing . . . . . . . 43
In this chapter the results from the simulations are presented and discussed. Simulations of
different types of structures are made using both the vector model and the scalar model and
some of the differences between the models are described.
3.1 Scalar Model Results
This section presents the results from the numerical calculations based on the scalar model
described in Sec. 2.2. The results are shown in Fig. 3.1 through Fig. 3.3. In all images the
origin of the coordinate system lies in the middle of the image. The positive x-axis is to the
right and the positive y-axis is up. In all cases the SPP is incident from the left.
3.1.1 Single Particle Scattering
In Fig. 3.1 the simulation of single particle scattering of SPPs is shown. This image should be
compared to Fig. 2.8(c) where the high intensity fringes are calculated analytically. The two
images of course correspond to each other, since they are manifestations of the same theory.
Fig. 3.1(a) shows the same single particle scattering for a gaussian beam. The same features
are replicated in this image. In Fig. 3.1(b) the scattering of a plane wave is shown. The
bending of the phase fronts are in both cases due to interference between the incident plane
wave and the scattered isotropic cylindrical wave.
Near the scatterer the phase fronts are very clear but far left from the scatterer they become
less clear. This is because the intensity of the scattered wave decreases as 1/r where r is the
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