Reply To: Single mode condition waveguide

[Guilin Sun]

The slab mode is from the 1D slice of the waveguide. It is not necessary here to introduce such 1D slab mode I believe.

I guess its meaning is, if you decople the 2D mode into 2 1D slab  modes, the first slab mode should have larger effective index than the 2D cross section of the real waveguide. the 2nd slab mode has about the same effective index as the 2D mode. such concept is used in VarFDTD: https://optics.ansys.com/hc/en-us/articles/360034917213-MODE-2-5D-varFDTD-solver-introduction