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help in FDTD for calculating propagation constant

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red5000

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propagation constant

i'm looking for any program to calculate the propagation constant with FDTD, and thanks
 

waveguide fdtd

help me, any adeas please.
 

fdfd waveguide

I maybe do not quite understand what you are asking. Do you want to calculate the propagation constant of a waveguide mode? If so, is there a reason you want to do this with FDTD? I would suggest looking at a frequency-domain tool like the finite element method (FEM) or finite-difference frequency-domain (FDFD). A frequency-domain code can very easily solve an eigen-value problem where the eigen-values are your propagation constants. What type of waveguides are you interested?

I will keep this e-mail short incase I do not understand what you are interested in.

-Tip
 

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    red5000

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numerical values for propagation constant

my professor require to me to use the fdtd method for calculate the beta (propagation constant), and the waveguide is a finline.
 

waveguide fdtd

Calculating the propagation constant (beta) of a guided mode using FDTD works backwards from what you may be thinking. Instead of FDTD giving you beta, you will give FDTD the beta quantity and it will compute the modes that result. Essentially, you will iterate this method until the mode you are interested in falls onto the frequency you are interested in. The algorithm works like this:

1. Pick a beta
2. Run 2D FDTD with d/dz=i*beta
3. FFT the time response
4. Look for peaks in the FFT. These are your modes
5. The beta you assumed is the beta of the mode you just calculated.
6. Adjust your beta and rerun FDTD until the frequency of the mode is the frequency you are interested in.

Here are two references:

Min Qui, "Analysis of Guided Modes in Photonic Crystal Fibers Using the Finite-Difference Time-Domain Method," Microwave and Optical Technology Letters 30(5), pp. 327-330 (2001).

T. Ando, "Eigenmode Analysis of Optical Waveguides by a Yee-Mesh-Based Imaginary-Distance Propagation Method for an Arbitrary Dielectric Interface," J. Lightwave Technol. 20(8), pp. 1627-1634 (2002).
 

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    red5000

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propagation constant beta

thank you for your help, do you have any pattern program for beggening.
 

how to calculate mode in fdtd

I do not have these codes, but I am interested in writing one for modeling very large waveguides. If/when I do, I would be happy to share my code.

-Tip
 

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    red5000

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how to find modes in 2d fdtd

thank you, and if you have e-books in this domain could you please help me with it.

Added after 5 minutes:

and could you please upload the two papers of qiu and ando.
 

propagation constant beta for a waveguide mode

Here are three papers...

Unfortunately, I don't have any e-books.

-Tip
 

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    red5000

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calculating propagation

rrumpf said:
I maybe do not quite understand what you are asking. Do you want to calculate the propagation constant of a waveguide mode? If so, is there a reason you want to do this with FDTD? I would suggest looking at a frequency-domain tool like the finite element method (FEM) or finite-difference frequency-domain (FDFD). A frequency-domain code can very easily solve an eigen-value problem where the eigen-values are your propagation constants. What type of waveguides are you interested?

I will keep this e-mail short incase I do not understand what you are interested in.

-Tip
Click to expand...

Hi,

Can you please explain how to find propagation constant solving eigen value problems with FEM? Or any references that you advise?

thanks
 

optiwave fdtd

solving an eigen-value problem with FEM is easier and harder. It is harder in the sense that FEM requires more upfront work formulating the equations you type into the computer to build the matrices. It is easier in the sense that once you have the matrices, you can simply solve for the eigen-values (propagation constants) and eigen-vectors (the mode profiles) and the answers fall right out.

What type of waveguide are you analyzing? If you are just starting out, can I recommend a frequency-domain finite-difference method?

For a good ebook on numerical modeling, try this...

**broken link removed**

-Tip
 

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    red5000

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fdtd of waveguide

rrumpf said:
solving an eigen-value problem with FEM is easier and harder. It is harder in the sense that FEM requires more upfront work formulating the equations you type into the computer to build the matrices. It is easier in the sense that once you have the matrices, you can simply solve for the eigen-values (propagation constants) and eigen-vectors (the mode profiles) and the answers fall right out.

What type of waveguide are you analyzing? If you are just starting out, can I recommend a frequency-domain finite-difference method?

For a good ebook on numerical modeling, try this...

**broken link removed**

-Tip
Click to expand...

Hi,

Thanks for the book, I've already started to study photonic crystal waveguide with FEM. So now dont have chance to do this with FDTD.
 

how to find propagation constant

thanks
 

optiwave fdtd rapidshare

you can try use optiwave fdtd to find every thing aboutv guiding mode in photonic crystal waveguide

good luck :D
 

    R

    red5000

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waveguide propagation constant

Does Optiwave FDTD have a way to distinguish degenerate modes? That is, can it separate distinct modes that happen to have the same propagation constant?
 

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    red5000

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fdtd fdfd

i don't know what is Optiwave FDTD ??

Added after 8 minutes:

but i'm looking for an algorithm with fdtd
 

optical waveguides: numerical modelling with fdtd

help
 

how to find propagation constant in waveguide

i'm looking for an algorithm with fdtd please
 

fdtd optiwave

Unfortunately, I have not written this form of FDTD. You may look for codes that go along with Taflove's book on FDTD, but I do not know if you will find it there. If not, you have three options: (1) you can purchase an off-the-shelf software; (2) you can pay somebody to write the code for you and provide you the code; or (3) be satisfied with a different modeling approach like FDM or EM where codes are available online. I suspect in these tough economic times, there would be plenty of individuals willing to write the code for you.

-Tip
 

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    red5000

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