I am struggling to simulate light propagation through a 3D fiber containing couple of cylinders perpendicular to its axis which form a kind of FBG in 1550nm, as shown in the picture:
the fsp file is attached here:
KMA_FBG100_3D.fsp (2.5 MB)
I used a fundamental mode source and detectors in order to measure reflection and transmission. Simulation is performed in 3D. I set the boundary condition as PML by taking advantage of symmetry in Y and Z axis to reduce calculation. The mesh accuracy is set to 3 for faster calculation.
The autoshutoff level seems set right because it reduces down to 0.001 finally.
But there is some problems here
1- when the number of cylinder is low (eg. 100) the peak in reflection seems reasonable (R~0.5). But when I increase it up to 500 cylinder, R goes beyond the unit!!! this happen even in 2D version.
2- the spectrum should has one peak at reflection, but the simulation contains two peaks!
3- Is there another method like Eigenmode Expansion method using “Mode” software or considering one unit cell like the one in example:
Thank for kind help