IN FDTD METHOD--how to implement gauss beam to TF/SF

[xingangahu]

IN FDTD METHOD--how to implement gauss beam to TF/SF

can someone tell me how to implement Gauss Beam to TF/SF ,i confused about that method, can you tell me what's the difference from normal TF/SF
THANK YOU!

 

[xingangahu]

anyone know it？？？

 

[mjl23]

What does TF and SF stand for? i am currently working on Writing these programs and have a lot of literature may be able to dig something up!

 

[xingangahu]

Total field scatter field

 

[iyami]

> can someone tell me how to implement Gauss Beam to TF/SF ,i confused about that method, can you tell me what's the difference from normal TF/SF
> THANK YOU!

I don't know how well you understand the TF/SF method but basically the type of source is irrelevant.
Essentially you add your source terms at the boundary by adding them to the fields which are lying in
the scattered field part when you have cells straddling the boundary.

What remains is to find an analytic expression for the fields in your source. This could be looked up e.g.
on wikipedia.

 

[xingangahu]

thank you for your reply! iyami

IN FDTD method implement plane source with TF/SF method is ok for me !

through the analytic expression has been got but how to implement the gauss beam ,some papers used the TF/SF method ,how to modify!

can tell detail!

 

[iyami]

Somewhere in your TF/SF code you have special updates for the fields at the TF/SF boundary.
They look like

HX = HX + c1 * (EY(top) + f(t) - EY(bttom)) + c2 * (EZ(back) - EZ(front))

where c1,c2 are some possibly negative constants and
f(t) is the source term you want to add
Here I assume that all field values except for EY(top) are in the TF region, only EY(top) is in the SF region
If you have a planewave f(t) is an analytic expression for EY at location top and time t. Replace this by
an analytic expression for your Gaussian beam and your done

Basically at locations where you mix scattered and total field values in a single update equation you adjust all
scattered values by adding source terms appropriate for the respective time step and location

 

[xingangahu]

thank you! iyami!

i understand that !

just the same as the taflove's book!
i will test it !

thanks again!