Meshing for Distributed Bragg Grating Filter in COMSOL

[haver]

Hello everyone!
I am simulating a distributed Bragg grating filter using comsol. The mesh i used is like wavelength/index/8, but i do not get symmetric spectrum to Bragg wavelength.Layers are λ/4 width. Is there a special meshing for these Bragg layers? Or is there someone who can give me suggestion?
Thank you.

 

[jsgruszynski]

You probably need to mesh smaller.

One trick: if you have a particular section of a system that has a large difference in critical physical dimensions within a larger piece of material, you can define a faux structure around that critical section (of the same material) and tell Comsol to mesh that volume smaller but then use a larger mesh for the larger dimensioned pieces. This can have a radical improvement on both accuracy and simulation time.