I have a periodic photonic crystal structure as a base, and I have a piece of standalone object on top of the PhC. Can I use periodic boundary conditions?
If the periodicity is broken due to the presence of the standalone object, I don’t think periodic boundary condition should be used here. When periodic boundary conditions are used, everything in the simulation region is copied to the next cell. If you cannot draw a unit cell, you should not use periodic boundary conditions.
However, including infinite number of photonic crystal (PhC) holes in the simulation is not practical. In this case, I would suggest setting up the simulation like this example file, and screenshot. This will include a finite number of holes to make the PhC, and the standalone object, using PML boundary conditions. That way you can simulate the defect on the periodic PhC, with this approximation.
To start with, I would recommend using only a few of the holes for testing, e.g., 6x6. With a finite number of holes, some physical effect due to the finite periodic arrangement can be present. To obtain results closer to the reality, you could trying using more PhC holes in the simulation. To do that, you will also need to increase the simulation span to take more holes in the simulation region. The simulation may need more memories and time to finish. Once the number of PhC holes has reached a certain number, increasing the number of holes would have a minimal influence on the local effects due to the presence of the defect. But it would not be easy to determine how many PhC holes you will need until you start to observe results convergence, by increasing the number of holes. Our OLEDs examples in the Knowledge Base might be able to give you some tips on how to set up this simulation.
PhC_defect.fsp (262.8 KB)