Open questions in regard to waveregime solver

[gomezzz]

Feature

Desired Behavior / Functionality

Please identify literature / answers to the following questions in relation to the FDTD solver.

Not urgent but long-term interest.

What Needs to Be Done

• [x] In which wavelengths, materials etc. is this applicable?
• [x] What are tunable parameters in terms of numerical accuracy, runtime?
• [x] How do we deal with courant number (not relevant in RCWA)?
• [x] How do we deal with permeability (not relevant in RCWA)?
• [x] Which parts of the computation are most expensive (can be come its own issue at some point)

[torbjornstoro]

Regarding runtime, the following variables is of importance:

• Grid size, i.e. points in grid in X and Y direction
• Number of steps in each simulation
• Two runs or one per frequency
• Possibility of two runs covering a range of frequencies?

[torbjornstoro]

The Courant number is proportional to the number of time steps per space step. More precisely S_c = c * delta t/delta x. The upper limit is 1 in 1D, 1/sqrt(2) in 2D and 1/sqrt(3) in 3D. It is set automaticly by the fdtd to the upper limit. Changing this to a lower value will ???

[torbjornstoro]

I think the relative magneic permeability can be assumed to be 1 for most cases, assuming thetemperatures in consideration is fairly high (well above room temperature). The relative magnetic permeability is defined as 1+ magnetic suspectibility. Magnetic materials can be classified into paramagnets, diamagnets, ferromagnets ferrimagnets and antiferromagnets. For paramagnets, ferromagnets, ferrimagnets and antiferromagnets, the suspectibility is proportional to 1/T or 1/T^2 (for the three latter this is only the case above a certain temperature, which usually is relatively low). Thus the susceptibility approaches zero and the permeability can be approximated to 1. For diamagnets, the susceptibility is constant, but usualy really low, so this magnetic permeability can also be approximated to 1.

[gomezzz]

@torbjornstoro check boxes where known