Photonics

Photonics

Convergence for Lumerical FDTD “Fluorescense Enhancement” example

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    • Justin Gruber
      Subscriber

      Starting from the Fluorescence Enhancement example, I first reduced the mesh size from 5 nm to 2.5 nm, and got similar results to those provided in the example. However, upon reducing the mesh size further to 1.25 nm my results start to seemingly get worse. At 1.25 nm mesh size, my results are outside of the +- dz error curves given in the script fluorescense_enhancement_comparison_theory. Would anyone be able to try to replicate these results or tell me where I am going wrong? The only settings I am changing are the mesh size and span of the mesh override region.

    • Guilin Sun
      Ansys Employee

      Convergence teating can be very challenge as there are several factors.

      I would suggest that you do not change the override size; make sure the dipole is located at the same Yee mesh location each time correspondent to its polarization; and make sure you have thick enough PML. You can roughly measure PML thickness with the ruler on the left hand side, the tool bar. PML should be half or motr wavelength  thick as dipole radiation in 4pi space.

      • Justin Gruber
        Subscriber

        Hello, I set the PML to have a thickness greater than half the max wavelength, but I am still having issues. When I change the material to silver, my results are not within the +-dz error curves that are mentioned in the example. 

        What exactly do you mean by making sure the dipole is at the same Yee mesh location corresponding to its polarization? I have been adjusting the mesh region to ensure it is halfway between two cells in the z-direction as described in the example at https://optics.ansys.com/hc/en-us/articles/360042161033-Fluorescence-enhancement.

    • Guilin Sun
      Ansys Employee

      As the image shows, for Ez polarized dipole, it must be located at Ez Yee cell:

       

       

       

       

       

       

      gs_intro_yee2.png  

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