Vector Finite Difference Mode Analysis



Does the bent waveguide option in MODE solutions have a “Fully-vectorial finite difference mode solver”?
I need to apply this analysis to structures with cylindrical symmetry to find the mode effective index, distribution, and bending loss. Even with a simple silicon waveguide the bend radius can’t be decreased in MODE beyond 5 um. Is there any way to find the properties of a tightly bent waveguide?


I would like to add something I have just learned about the Minimum bend radius:

So, the trick is to set the simulation span to be less than the desired radius. I applied this to the attached file. Now, I can study the bend modes down to a radius of 2 um.
BendRadius2um.lms (239.6 KB)

  • However, the solver can’t find modes for radii less than 2 um although the simulation span is 1.2 um. Can anyone help me with that?

  • If I want to study the modes in a disk resonator, the bend radius will be equal to slab width.


When I tried the file that you provided I was able to find modes with bend radius less than 2 um (I tried a bend radius of 1.5 um and 1 um and both worked).

Perhaps you could check the version of MODE Solutions that you are using since the sparse matrix solver used in the mode solving calculations was updated in one of the recent releases.