File:Speckle vs disorder.gif

\[Lambda] = 0.5;
k0 = (2 \[Pi])/\[Lambda];
c = 1;
\[Omega] = c k0;
\[Alpha] = (4 I)/k0^2;
\[Sigma] = (k0^3 Norm[\[Alpha]]^2)/4;
G[r_] := N[I/4 HankelH1[0, k0 Norm[r] ]];
source[{x_, y_}] := E^(I k0 x) E^(-((y - 0)^2/(2 0.5^2)));
dim = 50;
dipolesfixed = RandomVariate[UniformDistribution[{{-2, 2}, {-3, 3}}], {dim - 1}];
sinstep[t_] := Sin[\[Pi]/2 t]^2;
p0 = Table[
   dipoles = Join[dipolesfixed, {{-2 sinstep[t], 0}}];
   y0 = 0;
   E0 = Table[source[dipoles[[j]], y0], {j, 1, dim}];
   ME = Table[If[k == j, 0, \[Alpha] k0^2 G[dipoles[[j]] - dipoles[[k]] ] ], {j, 1, dim}, {k, 1, dim}];
   Es = Inverse[IdentityMatrix[dim] - ME].E0; (*Es=E0+ME.ES\[Rule]Es=(1-ME)^-1.E0*)
   Etot[x_, y_] := source[{x, y}] + \[Alpha] k0^2 Sum[G[{x, y} - dipoles[[j]] ] Es[[j]], {j, 1, dim}];
   DensityPlot[Abs[Etot[x, y, y0] ]^2, {x, -10, 10}, {y, -10, 10}, PlotPoints -> 100, ColorFunction -> "AvocadoColors", Frame -> False, PlotRange -> {0, 1.1}, Epilog -> {Purple, Point[dipoles], Black, 
      Disk[{-2 sinstep[t], 0}, 0.15], Orange, Disk[{-2 sinstep[t], 0}, 0.1]}]
   , {t, 0, 1, 0.02}];
ListAnimate[p0]