# Input Wave

## Incident Wave Source Excitation – Total/Reflected Field Formulation

The FDTD numerical scheme yields the solution of an initial value problem. At the first time step of the simulation all the fields are set to zero. The algorithm needs the initial field excitation that will be propagated through the computational domain. The FDTD Total/Reflected Field formulation gives the methodology in defining a +Z propagating…

## CW Excitation

In CW excitation, the time dependence of the incident field is a single frequency sinusoidal function. For example the incident Ey field has the following form: where A is the field amplitude, AF(x, zinc) is the transverse field distribution at the incident plane location zinc. The initial phase offset θi is the phase difference between points in…

## Pulsed Excitation

For pulsed excitations the incident field has the form: where is the pulse envelope function, toff is the time offset and t0 is the pulse width parameter. For pulsed excitations the time stepping continues until the desired late-time pulse response is observed at the field points of interest.

## Point Source

This version of OptiFDTD includes a new type of excitation – Point Source. Point source can also be referred to as a radiation source. For this new source, the input wave is only functional with one field component at one single point. You can specify which field component is required to add this source. In the case…

## Gaussian Beam Size

In OptiFDTD, transverse Gaussian Beam is expressed as where x0 is the center position and T is being called as half width. In general, Gaussian Beam radius is the radius at which the field amplitude and intensity drop to 1/e and 1 / e2, respectively. Gaussian Beam Size or Gaussian Beam Spot size is the beam…

## 2D Total Field / Scattering Field (TF/SF) Region

The Total-field/Scattered-field (TF/SF) technique results from attempts to realize any tilting plan-wave source that avoids the difficulties caused by using either the hard source or the boundary conditions. 2D TF/SF is a special type of formula that generates a wave in the enclosed rectangular surface. Inside the rectangular region, it generates the total field (including…