fields.colocate_amplitudes

Compute the forward- and backward-propagating wave amplitudes at z_offset.

The calculation is for a batch of amplitudes, with the batch dimension being final dimension.

forward_amplitude_start: The amplitude of the forward eigenmodes at the start of the layer, with a trailing batch dimension.
backward_amplitude_end: The amplitude of the backward eigenmodes at the end of the layer.
z_offset: The location where the colocated amplitudes are sought, as an offset from the start of the layer.
layer_solve_result: The result of the layer eigensolve.
layer_thickness: The thickness of the layer.