Learning Forum

[Muhammad Danial Haziq Azizan]

Hello

I'm plotting the band structures of a photonic crystal structure having a hexagonal lattice with hole arrays in a silicon slab.

Here is my question:

1. How do we know about the number of bands (10 bands in the example file given) in the band structure graph? Which band gives effect in bandgap? How to position the time monitor for band structure? it is just a random location?
2. Since on x-axis is in Gamma-M-K-Gamma, how to get other data from 0 until 0.5 (kx normalized) like in this example "Bandstructure of photonic crystal waveguide - Line defect"? Is it possible to use the same script? I already tried it and got the error when simulated. 
3. For the dipole source, how to position it? Is it just a random location? Why in example only need 6 sources? Any explanation for more detail cause I don't understand clearly about this.
4. When I remove W1(remove a row of air holes), I obtain 3 bandgap but in a straight line. It's correct? Why is it not in a curved line? Any guidance? 
5. 

[Guilin Sun]

A1： A photonic crystal can have many bands. But usually people are interested in the 1st and 2d band. I believe you will have your own purpose for simulation. Bandgap can be full or partial. Please check your own desire. Both dipole and monitor clouds are random to avoid possible issues.

Please get more information from the website, such as https://optics.ansys.com/hc/en-us/sections/360006919074-Photonic-crystals

A2: we have examples and script files for most cases. Please refer to the above link.

A3: the number of dipoles is to make sure all the bands can be excited, You can try different numbers if the band structures have issues, such as missing points, too many off band points etc. the monitor is the same.

A4: please refer to this exmple: https://optics.ansys.com/hc/en-us/articles/360042038473-Bandstructure-of-photonic-crystal-waveguide-Line-defect

Please check the settings. Might be the K vector values are wrong, or the k points do not applly to the dipoles. Please compare the settings of your file and the example.