This page provides a basic introduction to the sources in FDTD Solutions (with images of the steady state (CW) field profile and movies of the time domain pulse for each source). Sources in MODE Solutions’ propagator are very similar but may look slightly different since they do not have z-dependence.
Dipoles
Dipoles are used to simulate point source radiators, such as radiation from a fluorescent molecule. There are two types of dipole source: Electric (oscillating point charge) and Magnetic (current loop). The radiation pattern of these dipoles is similar, but not exactly the same. For more dipole source information, see the Sources - Dipole page.
Gaussian beam
The gaussian beam source is typically used to simulate a focused beam incident on a structure. In this example we show a beam with a numerical aperture (NA) of 0.6 focused at a point 7μm in front of the source injection plane.
To reproduce the movies, run the associated simulation file. To create the CW field profiles, select the appropriate monitor to visualize the fields.
Plane wave
The plane wave source is typically used to simulate very large (approximately infinite) beams incident on periodic structures. Periodic or Bloch boundary conditions are normally required. In this example we show a plane wave traveling at a 30 degree angle of incidence in a 2D simulation. For more planewave source information, see the Plane waves - Edge effect page.
To reproduce the movies, run the associated simulation file. To create the CW field profiles, select the appropriate monitor to visualize the fields.
TFSF
The TFSF source is typically used to simulate very large (approximately infinite) beams incident on finite (non-periodic) structures. The scattering structure must be completely contained within the TFSF source. In this example we use a TFSF to see the scattering from a cylinder in a 2D simulation. For more TFSF source information, see the TFSF page.
To reproduce the movies, run the associated simulation file. To create the CW field profiles, select the appropriate monitor to visualize the fields.
MODE
The MODE source is used to inject a guided mode into a device, such as a waveguide. In this example we use the Mode source to inject a 2nd order mode into a step index fiber in a 3D simulation.
To reproduce the movies, run the associated simulation file. To create the CW field profiles, select the appropriate monitor to visualize the fields.
Import (custom) source
The Import source allows the user to import a custom source spatial field profile, which may be obtained from a monitor in another simulation, or calculated analytically.
To reproduce the movies, run the associated simulation file. To create the CW field profiles, select the appropriate monitor to visualize the fields.