how can I make a defect in a PhC?


how can I make alternative defect in the photonic crystal structure?



The best approach to achieve the structure with a defect will be the use of a script. Lumerical FDTD solutions employ a scripting language to help in defining the structures and also post-calculation analysis. Do you want to remove any of the dielectric circles or change the symmetry around the defect site?

If you can give more details, I can help you.



We also have a bunch of structure groups in the Object Library that you can use, either directly or as a starting point to build your own photonic crystal with a defect.


I want to remove any of the dielectric circles. for example, 6 dielectric circles



As fgomez mentioned in his earlier post, Lumerical provides a group of structure groups. These are essentially user-friendly scripts packed in a graphical interface that allows for the incorporation of common photonic or other structures. The script actually automates the creation of the dielectric cylinders and define the material.

For your custom photonic crystal, you can suitable modify this script to achieve the desired structure. Alternatively, you could use ARRAY button to create an array of CIRCLES and disable/delete the ones you don;t want.

Here is also a knowledge base article on creating an array with the help of script, that will be of interest to you.

Best Wishes,



I did but I face to another problem.


Hi Moslem,

The reason why you see this message is that the structure group you are trying to modify is a construction group. You can learn more about construction groups here:

If the changes you need to make to the structure cannot be done by adjusting the properties of the group you need to modify the setup script itself. Alternatively, you can uncheck the construction group option to be able to modify the objects inside the group.


I did but I can just disable the object and I can’t move them,why?

thank you for helping,


Hi Moslem,

What is happening is that everytime you modify the elements in the structure group, the setup script of the group is run again. If you check the setup script it has a command that deletes all the structures in the group and a command that creates the circles again. Therefore, if you try to move one circle, the structure group reruns the setup script deleting all the circles and redrawing them at the original positions.

One quick workaround is to place all the command lines of the setup script inside a


# Script lines here


so that they are not rerun. If you need to rerun the script you can change the 0 in the conditional to 1.

Alternatively (and probably much better in the long run), you can modify the setup script itself so that the changes you make are built in the structure group.