Learning Forum

[zahra mansouri]

i am simulating a cylinderical waveguide in lumerical mode solution. when i change the mesh step or change the simulation region the answer (neff) change. i use a override mesh for my structure. and i set my simulation region about 1.5 of wavelenght. how can i choose best mesh setting and best simulation region for my structure? i use a 2d sweep for neff that one of them is for maximum mesh step in overrride mesh setting and another is simulation region. with that result i can see a region that neff is constant in it. is it a true method for finding best setting or not?

[Guilin Sun]

The simulation region depends on the modes you desire. If the modes are well confined in the core the simulation can be small. Using override region only for the core region or where the modes reside. 

If the result changes with simulation region or mesh size, please do a converging test. the real part should be accurate at 4th decimal for rough testing. You can do such converging test later once the result is promissing. No need to do this for every design to improve simulation efficiency.

Your method is good for converging test.