Hi,
I need to realise/fabricate very high-Q photonic crystal cavities in silicon for my PhD project. The cavities should be optimised for certain wavelength range (around 1078 nm). I am trying different designs and optimise them to find out most suitable one in terms of fabrication. But fine meshed 3D FDTD takes very long time to simulate. I was wondering if 2D simulation gives at least qualitatively reliable results. If so, how should I set the simulation parameters. As I am doing the fabrication myself, I do not have enough time to explore FDTD method and how it works in detail. So, any suggestion/comment on solving/simulating this photonic crystal cavities would be very helpful.
Thanks in advance.
Salahuddin
Depending on your structure, a 2D simulation should work very well. You can approximate the 3D circuit as a 2D circuit using the effective index method. You will have to make sure that the lattice you predict in 2D still has a band gap and adjust accordingly. You can see a picture of the effective index method minus the photonic crystal in Lecture 20, Slide 4 here:
http://emlab.utep.edu/ee5390fdtd.htm
If you are reducing your simulations to 2D, consider using the finite-difference frequency-domain (FDFD) method. Depending on the size of your devices, the FDFD method should prove you much faster simulations for highly resonant devices because it is a frequency-domain method. You can learn about this method in Lectures 11 to 13 here:
http://emlab.utep.edu/ee5390cem.htm
Hope this helps!
Dear Professor Rumpf,
Thank you very much for your suggestions. I will try to do accordingly.
Many Thanks,
Salahuddin
3D circuit can be approximated as a 2D circuit using the effective index method, but the losses and then the Q factor is under-estimated because the diffraction losses in the top and the bottom of the circuit is not take into account. We can also use Mode Matching Method like use in fimmwave.
If your simulation involves nanoparticle or dipole source, it is better to do 3D.
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