Learning Forum

[Rajat Kumar Sinha]

Hey, I am trying to find the effective index of a mode inside the waveguide which has a grating on top. The waveguide looks something like

waveguide.png

[Kyle]

The FDE solver in MODE calculates waveguide modes assuming that the refractive index cross-section is constant along the direction of propagation, for straight, bent and helical waveguides. If there is a grating this means the index cross-section is changing, so FDE can't be used. For this reason, typically FDTD or EME would be used for simulations with gratings. We have some examples of grating and photonic crystal simulations available in our Application gallery here that might be helpful for you: https://support.lumerical.com/hc/en-us#app-anchor