I want to simulate a substrate uniformly embedded with GaAs quantum dots and would like to approximately consider the quantum dots as two-level systems with the saturable absorption effect. Now I am trying to find a material model in FDTD to simulate such a system and I found this “Two-level one-electron example” in “Available material models” under “Advanced Material models” page in Lumerical Knowledge Base as shown below.
But in simulations this model didn’t show any change in the system’s index of refraction for any different source intensity(I set omega0=2e15=input source frequency, gamma=1e11, gamma10=1e9, Nd= Ie21).
So could you please provide a more detailed formula to describe the index of refraction this model can give in terms of these input parameters? Also, can this model be used to simulate a saturable absorption material? If not, what model should I use? Thank you so much!