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scattering.ScatteringMatrix

Class scattering.ScatteringMatrix():​

Stores the scattering matrix for a stack of layers.

The first layer in a stack is the "start" layer, and the last layer in the stack is the "end" layer.

The scattering matrix relates the forward-going and backward-going waves on the two sides of a layer stack, which are labeled a and b respectively.

Note that forward going fields are defined at the start of a layer while backward-going fields are defined at the end of a layer, as depicted below. This is discussed near equation 4.1 in [1999 Whittaker].

        |             |           |         |           |
        |   layer 0   |  layer 1  |   ...   |  layer N  |
        | start layer |           |         | end layer |
        |             |           |         |           |
         -> a_0                              -> a_N
                b_0 <-                            b_N <-

Following the convention of [1999 Whittaker], the terms a_N and b_0 are obtained from,

            a_N = s11 @ a_0 + s12 @ b_N
            b_0 = s21 @ a_0 + s22 @ b_N

Besides the actual scattering matrix element, the ScatteringMatrix stores information about the start and end layers, which are needed to extend the scattering matrix to include more layers.

Args:​

  • s11: Relates forward-going fields at start to forward-going fields at end.
  • s12: Relates backward-going fields at end to forward-going fields at end.
  • s21: Relates forward-going fields at start to backward-going fields at start.
  • s22: Relates backward-going fields at end to backward-going fields at start.
  • start_layer_solve_result: The eigensolve result for the start layer.
  • start_layer_thickness: The start layer thickness.
  • end_layer_solve_result: The eigensolve result for the end layer.
  • end_layer_thickness: The end layer thickness.