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fields.directional_poynting_flux

fields.directional_poynting_flux​

Returns total forward and backward Poynting flux.

This function decomposes the total field into components resulting from the the eigenmodes with positive and negative Poynting flux, and returns the time-average flux in each order for these two components. The calculation follows section 5.1 of [2012 Liu].

In the general case, a forward eigenmode may actually have negative Poynting flux, and so e.g. it may occur that a one-hot forward amplitude vector yields zero forward flux and nonzero backward flux.

If the flux associated with the forward and backward eigenmodes is desired, amplitude_poynting_flux should be used instead. This function serves the more typical case where the total forward flux and total backward flux is desired.

Args:​

  • forward_amplitude: The amplitude of the forward eigenmodes, with a trailing batch dimension.
  • backward_amplitude: The amplitude of the backward eigenmodes, at the same location in space as the forward_amplitude.
  • layer_solve_result: The results of the layer eigensolve.

Returns:​

  • None: The Poynting flux associated with the forward and backward eigenmodes.