Spectral filter

[HaraldRedlin]

Is there a method available to simulate the effect of a spectral filter / frequency filter for beam transport?

[tinolang]

You can easily apply spectral filters between subsequent components (in your code different objects of the chi3d class).

For example, the spectral field returned by one object, e.g.

[~,Eftfxfy]=run(SHG,{'pulse1'});

is a matrix with the dimensions [Nt,Nx,Ny].

Spectrum_alpha0 =  abs(Eftfxfy(:,end/2,end/2)   ).^2;
subplot(2,1,1)
plot(SHG.constVect.lambda,Spectrum_alpha0),xlim([490e-9 510e-9]); %use getSpectrum for the accurate intensity distribution

shows the spectrum of all k-vectors pointing exactly along the z-direction (alpha=0 -> fx and fy = end/2).

The easiest way to filter optical frequencies could be a simple square function applied to the ft dimension of the matrix:

Eftfxfy(SHG.constVect.lambda<499e-9 | SHG.constVect.lambda>500.5e-9,:,:)=0;
Spectrum_alpha0 =  abs(Eftfxfy(:,end/2,end/2)   ).^2;
subplot(2,1,2)
plot(SHG.constVect.lambda,Spectrum_alpha0), xlim([490e-9 510e-9]);

You can also multiply a complex filter function to the original electrical field in the spectral domain, e.g.

Eftfxfy = meshgrid(spectralFilter,1:Nx,1:Ny).*Eftfxfy;

In this case spectralFilter can be a one dimensional complex vector, e.g.

spectralFilter= Transmission_ft .* exp(i * phase_ft);

The transparency during the simulation is defined by the chosen material (obj.simProp.material) and the data in Materials/medium_transmission.dat.