Diffraction efficiency as a function of lambda and theta for  a volume reflection grating

From Optical Imaging and Spectroscopy (Wiley - OSA 2009)
By David J. Brady
www.opticalimaging.org
Figure 9.22

dEps=5 10^(-4);
K=4 Pi ;
kz[dT_,dL_]:=2 Pi Cos[dT]/(1+dL);
gamma[dT_,dL_]:=Sqrt[dEps^2 kz[dT,dL]^2-(K-2 kz[dT,dL])^2]/2;
L=2/ gamma[0,0];
Eta[dT_,dL_]:=(kz[dT,dL] dEps/2)^2* Abs[Sinh[gamma[dT,dL] L]/(gamma[dT,dL] Cosh[gamma[dT,dL] L]- I (K-2 kz[dT,dL]) Sinh[gamma[dT,dL] L]/2)]^2;

dog=Plot3D[Eta[Pi dt/180,dl],{dt,-5,5},{dl,-.001,.001},PlotPoints->100,Mesh->False,Lighting->{{"Directional",GrayLevel[.8,.5],{{5,5,4},{5,5,0}}}},AxesLabel->{Δθ,Δλ},PlotRange->All]

dog=DensityPlot[Eta[Pi dt/180,dl],{dt,-3,3},{dl,-.0025,.0015},Mesh->False,PlotPoints->150,FrameLabel->{Δθ,Δλ},PlotRange->All,ColorFunction->Function[{dt,tl,z},GrayLevel[1-z]]]

Plot[{Eta[1Pi/180,dl],Eta[0,dl]},{dl,-.002,.001},PlotPoints->100,Axes->False,Frame->True,FrameLabel->{Δλ},PlotRange->All]

Plot[Eta[1.5 Pi/180,dl],{dl,-.001,.001},PlotPoints->100,Axes->False,Frame->True,FrameLabel->{Δλ},PlotRange->All]

dEps=10^(-6);
K=4 Pi ;
kz[dT_,dL_]:=2 Pi Cos[dT]/(1+dL);
gamma[dT_,dL_]:=Sqrt[dEps^2 kz[dT,dL]^2-(K-2 kz[dT,dL])^2]/2;
L=2/ gamma[0,0];
Eta[dT_,dL_]:=(kz[dT,dL] dEps/2)^2* Abs[Sinh[gamma[dT,dL] L]/(gamma[dT,dL] Cosh[gamma[dT,dL] L]- I (K-2 kz[dT,dL]) Sinh[gamma[dT,dL] L]/2)]^2;

Plot[Eta[0,dl],{dl,-.001,.001},PlotPoints->100,Axes->False,Frame->True,FrameLabel->{Δλ},PlotRange->All]

N[dEps/2]

Plot[Eta[dt,0],{dt,-.01,.01},PlotPoints->100,Axes->False,Frame->True,FrameLabel->{Δθ},PlotRange->All]

N[Sqrt[dEps]2]

Plot[Re[gamma[0,dl]],{dl,-.01,.01},PlotPoints->100,Axes->False,Frame->True,FrameLabel->{Δλ},PlotRange->All]