# Q Factor

Dear Optiwave Team,

I am a student that has been on placement at University and this software has been great to try designs of photonic crystals, thanks so much for making it available to try, and the 32 Bit version. My question is related to use of the 32 Bit version. Please excuse any naivety in this post, I am new to the world of FDTD software…

I have modeled a photonic crystal cavity (a H1 cavity comprising of array of GaAs pillars). Using the 2D band gap simulator I have the required band gap in the photonic crystal lattice for the modeled point source. I would like to know if I am calculating the Q factor correctly using the software, this is my method:

1. Positioning a point source in the center of the cavity

2. Placing an observation point in the cavity.

3. Running the simulation on the auto settings (I have also tried decreasing the mesh size and time steps to the memory limit of my computer). I run the simulation for 30000 steps which seems to allow the standing wave in the cavity to ‘settle’.

4. Then use the OptiwaveAnalyser software to perform observation point analysis. I use the FFT and DFT (with seemingly similiar outcomes) to perform the following: frequency/(FWHM) at the observation point.

I am getting very low Q factors of nothing higher than 480 at best…

I would like to make sure I am using a valid method to calculate the Q factor? Is this possible in 32 Bit version of Optiwave FDTD?

I hope you can help.

Regards,

Lucas

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