A personal implementation of 1-3D Plane Wave Expansion. This software was developped to understand PWE, it is not really efficient. If you are looking for this kind of software (but good), I recommand mpb.
I will implement hexagonal lattices soon but for know, you can get square lattices shown in Molding the Flow of Light.
Figure 2, Chapter 5 of Molding the Flow of Light (2nd edition), the dielectric rods.
Figure 5, Chapter 5, the dielectric veins.