how to create a spiral phase plate structure

fdtd

#1

Dear all,

I want to create a structure but don’t know how to do it.
The structure is attached below:

The equation for this structure is simple, but need to use cylindrical coordinate:
z=sphi/(2pi)
r<=a

I want to set s=2.1um, a=1um

Could someone help me with that?
Thanks a lot!


#2

Hi,

The way to import your custom structures is by following this protocol.

https://kb.lumerical.com/en/ref_sim_obj_structures_custom_optical.html

This allows you to create custom structures with the desired dimensions.

I hope this was helpful.

Best Wishes,

Vivek


#3

Thanks, Vivek.
But this is a 3d non-symmetric structure, I need all (x,y,z) or (r,phi,z) into equations to construct.
Both the Custom Primitives or Surface protocol can’t meet my criteria.
Does it mean that I could only build with other 3d model software, or I could use some scripts in Lumerical FDTD to make this structure?

Thanks again!


#4

Hi,

The other option you have is to draw it into a program that will support what you need and then import it into Lumerical in the form of STL file. This is how I have approached I have incorporated complex structures into Lumerical in the past.

Here is the knowledge base article for importing STL files:

https://kb.lumerical.com/en/ref_sim_obj_import_-_stl.html

I hope this is helpful.

Best Wishes,

Vivek


#5

Hi,

I’ve done it by the ring structure and using StructureGroup to realize the continuous spiral phase plate (adding the discrete steps # to approach the continuous one).
The result is attached as below:
CT SPP.fsp (1.1 MB)
Thanks for the helps!