Reply To: Compare effects of using constant real index vs a detailed material index

[Guilin Sun]

When you use a fixed refractive index across the source spectrum, it means all the wavelengths will not experience any dispersion. eg, for the same incident angle the exit angle is the same, if we use geometric optics to explain it.

Dispersive materials, on the other hand, will lead to different interaction.

As for the peak-valley, it depends on the phase change due to the slab. for the same optical path length, eg, fixed refractive index, the phase is different since phase is 2pi*OPL/wavelength. 

If you know a material is dispersive, you should use the dispersive model.

For thin film type devices, as suggested in another post, you can use stackrt to get accurate reflection and transmission, as long as you use the correct material model.