Detailed Instructions:

Attention, the simulation geometries can't exceed or touched the observation line. The distance larger than ten grids is better (for visible light region, as the simulation material is metal, there might exist strong evanescence wave on the metal surface. then the distance need to larger to this evanescence length)

There are four kinds of TFSF

TFSF-RCS (Typically)

The left figure of below shows Ex, Ez, Hy fields without any geometry inside. The incident wave from left bottom with theta = 65 degrees.

The right figure of below shows Ex, Ez, Hy fields with metal cylinder inside.

TFSF-RCS-Substrate

This technological is design for the TFSF with substrate condition. In experiment, the structure under test not always levitate in the air. For example, if we'd like to measure a sphere scattering effect, it might put on the substrate. However, if the substrate exist in the simulation space which show in the left figure below. The TFSF technological will encounter error which show in the right side figure below.

This will lead to a wrong simulation result. The incident wave error is from 1D look up table source don't give the substrate (refer to the FDTD book).

In GUI parameters, the substrate position means that we need set the top position in 2D or 3D simulation. The substrate can be made of dielectric, metal, or other dispersion material. As there isn't any geometry inside (free space), we can see if setup correct the wave will excite perfect and without any diffraction to outer side.

in this example, X can set at any position, but the Z position need to set at position = 50, it's the same to the substrate top side of simulation structure.

(Also can refer to Lumerical commercial software, it's the same theory in the TFSF wave incident with substrate.)

對照引用 Comparison & Reference：

Lumerical FDTD Solutions

Multi-layer stack with gap 

http://docs.lumerical.com/en/index.html?ref_sim_obj_tfsf_sources_examples.html

And here show the wrong example, the substrate position isn't set correct to the "1D look up table " in FonSinEM.

(TFSF-Line) (Load Mode Profile)

In TFSF-Line, if you'd like to excite a Gaussian beam, you can use the built-in function in FonSinEM. the Gaussian beam equation is

GaussianProfile=exp(-(x^2+y^2)/beamsize^2)

refer to Wiki

http://zh.wikipedia.org/wiki/%E9%AB%98%E6%96%AF%E5%85%89%E6%9D%9F

Gaussian beam 2D exmaple

＝＝＝＝＝＝＝＝ Parameters setup：2D ＝＝＝＝＝＝＝＝＝＝＝＝＝

Total Grids

X = 200

Z = 200

delta = 5 nm

Boundary condition

X: PML

Z: PML

Wave

CW, 100nm

TFSF-line

Source Position

X = 50

Z = 30

Mode Profile

GaussianBeam, Beam-Size : 100e-9

Polarization 1

Amp : 1

theta : 30

phase : 0

Cal. Time Step

2000

＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

Gaussian beam 3D exmaple

＝＝＝＝＝＝＝＝ parameters setup：3D ＝＝＝＝＝＝＝＝＝＝＝＝＝

Total Grids

X = 50

Y = 50

Z = 120

delta = 10 nm

Boundary condition

X: PML

Y: PML

Z: PML

Wave

CW, 100nm

TFSF-line

Source Position

X = 25

Y = 25

Z = 11

Mode Profile

GaussianBeam, Beam-Size : 100e-9

Polarization 1

Amp : 1

theta : 0

phi: 0

psi: 0

phase : 0

Cal. Time Step

1000

＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

SoftSource

Source can use for point, line or any other shape, but only one electric or magnetic can choice in a simulation.

2D TM (Ex Ez Hy) can choice Ex, Ez, Hy

2D TE (Hx Hz Ey) can choice Hx, Hz, Ey

3D (Ex Ez Hy) can choice Ex, Ey, Ez, Hx, Hy, Hz

Softsource means set a source on the choices position,for example : Ex

Ex = Ex + Js

if a reflection wave pass through the softsource position, the field will superposition.

The below figure means 2D TM, Hy point source (x=60:60,z=60:60), source is at center position, we can see the point source divergence (Huygens priciple).

Perfect electric conductor wavegudie mode excite example

【Input pannel】

m=1;

d=(ib-1)*gdx;

for i=2:ib-1 

LoadSource(i,jcenter,kcenter)=cos(m*pi/d*(i-2)*gdx); 

end