far field Transmission Spectrum

[Ma Po]

I want to calculate the (near) 0-th order far field Transmission Spectrum T(lambda) of a diffracting structure (periodic in x and z direction).
As I see I can calculate the fields in an output plane in near filed and normalize on the input plane in order to get T spectra here.
Also I can transform the into far field, but only for one wavelength at a time.

Is there a possibility (or script) to get many wavelength’s far field data ?

[Ma Po]

here is my basic model (OptiFDTD 32bit version):

Attachments:

1. far_field_transmission_spectrum_question.fdt

[Damian Marek]

I would start with this tutorial:

Diffraction Efficiency and Diffraction Angle Based on Grating Unit Cell

Also from a glance at your simulation I found that your Input plane and detectors were not placed optimally 🙂

When using PML boundaries you should try to keep the input plane and detectors away from the boundaries as this is where the field is being absorbed and will affect the accuracy of the simulations. Try keeping them about half the wavelength away and that should be sufficient.

Regards,
Damian

[Ma Po]

Thanks Damian,
for checking my model and your comments on the planes distance from the PML boundaries.

If I understand the example correctly, there is no way for doing the far field calculation for many wavelengths
in ONE action (or via a script) ?

Regards,
Markus

p.s. as I am using the 32 bit version – could you give me the 32bit version of mentioned example *Caululate_Grating_Efficiency.fdt ?

[Ma Po]

for clarity, here the total experimental setup.
Aim is to simulate the spectrometer (400-1000nm) measured
transmission spectrum, normalized on input intensities.

Attachments:

1. 

   setup.png
   

[Damian Marek]

There is no way to do the automatic far field transform for multiple wavelengths. Unfortunately you have to export each field individually and do the calculation manually. The example file I attached should also be in your samples folder with the same name.

Sorry for the slow response!

[Author]

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