Learning Forum

[kyo-cheol kang]

In the OLED field, Power Dissipation Spectra are typically calculated using Python or dedicated tools. 
Commonly used tools for this purpose include TechWiz from a different company or SETFOS from Fluxim, which can be used to obtain the Power Dissipation Spectra.
 As shown in Figure 1, it is possible to observe air, substrate, WG, and SPP modes simply from the graph.

Figure 1. Calculation results of TE- and TM-polarized power dissipation spectrum (The four regions of the air, substrate, WG, and SPP modes are marked in the different shaded colors of sky blue, gray, yellow, and pink.)

To find a similar feature in FDTD, I tried applying the example provided in the response at this link( https://innovationspace.ansys.com/forum/forums/topic/power-dissipation-spectra/ ). 
However, unlike the Python-calculated results shown in Figure 2(left python, right fdtd), I encountered the following issues with FDTD:

1.The intensity of the Dissipated Power is different.
This issue seems to be due to an error in the formula used to calculate the Dissipated Power. 
I am curious if there is a built-in function in FDTD that calculates this correctly.

2.Unable to calculate with normalized in-plane wavevector.
When sweeping the Bloch boundary condition value 𝑘 at each wavelength from 400 to 700 nm, the calculation is performed.

Afterward, I face difficulties in dividing the obtained k value by the wavelength to compute the normalized wavevector.

3. FDTD can only perform 1D calculations.
The example from the link uses FDTD in 2D, but with one span dimension made extremely thin, effectively making it a 1D calculation. However, since we need to calculate the dissipated power with a nanostructure in the future, I am looking for a way to perform this calculation in 2D.

Figure 2 .Dissipated Power Calculated by python (left) , by FDTD (right)

[Guilin Sun]

1: there is no script dedicated to this calculation;

2: k vector is not only associated to plane wave. Dipoles can also have it. It is specified to meet the bandstructure calculation. Bloch Conditions are good for one wavelength, since other wavelength will have different angles: Bloch boundary conditions in FDTD and MODE

3: current online examples are for band structure calculation, not for dissipation. and it uses symmetry of the Brillouin space thus it is not 1D, although you can simulate it in 1D. 

In summary, currently no example is presented online for such dissipation spectrum for OLED, and the exact algorithm and calculation formula are not known. If you can give more details we may provide some more help. It seems it will need new algorithm.

This website https://github.com/jsbangsund/oledpy has a tool for such calculation.

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