Learning Forum

[Greg Baethge]

This topic describes the CW normalization used to convert time domain data to frequency (steady-state) data. The CW normalization option should be used whenever you collect frequency domain information.

Solvers: FDTD, varFDTD

See also:

Sources

Units and normalization

Frequency domain normalization

Single frequency simulations in FDTD

Sources in FDTD always inject a pulse (i.e. broadband), even when the user is only interested in collecting data at a single frequency. Pulse sources are more efficient for collecting broadband information, and at least as efficient when collecting information at a single frequency. Therefore, there is no reason to use CW sources. The CW response of a structure can easily be obtained from a simulation that used a pulse source.

The following screenshot shows the source Frequency/Wavelength settings tab. In this screenshot, the source wavelength is set to a single frequency of 500nm. Even thought the frequency span is zero, a pulse is still used. The time domain signal of the pulse, and the associated power spectrum, are shown in the figures on the right side of the window.