Hello Park,
You are going to have to provide more information regarding what you have tried. There is a photonic crystal component called PBG Crystal Structure within OptiFDTD that supports 2D and 3D photonic crystals. Within it you can select an FCC structure and define your lattice constant and atoms.
We do have a number of photonic crystal references and tutorials:
- If you are using version 14.0 or later then tutorial number 3 in the manual walks you through the creation and analysis of a 2D structure.
- Lesson 3 in the OptiFDTD archives also provides walkthroughs <a href=”https://optiwave.com/category/optifdtd-manuals/optifdtd-background-and-tutorials/a5-lesson-3-photonic-crystal-and-photonic-band-gap/”>Link</a>
- We also have a number of webinars some of which include work with photonic crystals <a href=”https://www.gotostage.com/channel/optiwave”>Link</a>.