Gradient index profile in FDTD

I am looking for a gradient index profile in the FDTD solver, as there exists in the FDE solver :
Does such an option exist in FDTD?
Thank you,

Dear @colin.ducrotoy

Yes, you can simply copy-paste the objects from FDE into FDTD, and then use an index monitor to study the index profile of the objects. You can also add a port object, with similar geometry as FDE, to obtain identical results as you obtained for FDE simulations.

For your convenience I prepared similar geometry in FDTD (as exp-wg.lms in FDE):

exp-wg.fsp (358.3 KB)

Please let me know if you had further questions or any difficulties with FDTD simulations.