FDTD simulation validity

This topic has 12 replies, 7 voices, and was last updated 10 years ago by Damian Marek.

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- April 15, 2014 at 2:57 pm #10527
  
  Chao Zhang
  Participant
  
  Hi
  
  I am recently doing some EM simulation in the terahertz range. However, I am not very clear whether FDTD method is valid to do this job. So anyone can reply to me that if the FDTD product of Optiwave is able to do that. I know that this method is very popular in nanophotonics research. Terahertz structure should be much larger than the nano field. Thanks
- April 15, 2014 at 3:20 pm #10537
  
  Luis Acevedo
  Participant
  
  FDTD works ok in um and nm fields
  GHz is ok
  
  You can try to simulate something in OptiFDTD with this units.
- April 15, 2014 at 3:23 pm #10538
  
  Luis Acevedo
  Participant
  
  You should be ok in Terahertz, BUT, a big But
  You must analyse an um or nm structure in nearfield
  Try out a preliminary model
- April 23, 2014 at 2:01 pm #10890
  
  Aurelien Duval
  Participant
  
  It should be doable if you do not use predefined materials (such as metals etc) since they are defined in the visible-NIR range usually.
  The best way to ensure that is to try out our software. If you are ensure on what to do, simply post a link to a reference article and we’ll see if we can reproduce the results.
- April 23, 2014 at 2:44 pm #10896
  
  Luis Acevedo
  Participant
  
  yeah thanks for the note
- April 24, 2014 at 10:28 am #10915
  
  Azzouz Sellai
  Participant
  
  Hi
  Has anyone developed a FDTD simulation of a simple Otto or Kretschmann configurations for surface plasmons excitations? I am learning to use FDTD which seems quite different from COMSOL!
- April 24, 2014 at 11:52 am #10966
  
  Aurelien Duval
  Participant
  
  Hi,
  
  Here’s a pretty basic example.
  
  I use a SF10 glass prism to couple into a 50 nm thick layer of gold. The analyte is water at 1.33 and the wavelength is 633 nm.
  You’ll notice that the coupling conditions are not perfectly met, probably due to a slight change in refractive index of gold as compared to the source I used to determine the angle (57 degrees incidence from the vertical).
  
  What is important for this type of simulations is to mesh fine enough to resolve correctly the metallic layer (here I go down to 5 nm resolution, but it’s probably overkill).
  
  A note: performances will be horrible compared to simple analytical formulations (Fresnel reflection coefficients and Rouard method for example). It only makes sense if you geometry is not a simple uniform film.
  - December 8, 2014 at 1:40 pm #16446
    
    Duane Kaufman
    Participant
    
    Hello,
    
    My name is Duane Kaufman, and I am trying to teach myself the tools of Surface Plasmon Resonance detection.
    I have downloaded the free 32-bit version of OptiFDTD to familiarize myself.
    
    The prismKretschmann.fdt file posted on this thread would be a great start for me to get my feet wet, but my version of OptiFDTD cannot open this file (prismKretschmann.fdt cannot be opened. It was created with a newer version of OptiFDTD)
    
    Would it be possible to create this example in a format the 32-bit version could open?
    
    Your help is appreciated!
    Duane
    - December 8, 2014 at 2:42 pm #16449
      
      Damian Marek
      Participant
      
      Hi Duane,
      
      Try this file.
      
      Regards
    - December 8, 2014 at 5:33 pm #16452
      
      Duane Kaufman
      Participant
      
      Hello,
      
      Thanks for the file, it loads properly.
      
      Now I need to learn what I can!
      
      Duane
- April 24, 2014 at 12:31 pm #10975
  
  Luis Acevedo
  Participant
  
  Thanks for the example. I am learning a lot with you feedback.
- December 9, 2014 at 6:59 am #16478
  
  Sourabh Sahu
  Participant
  
  is it possible to simulate micro toroid and mico ring resonator using OptiFDTD
  - December 9, 2014 at 9:03 am #16490
    
    Damian Marek
    Participant
    
    Undoubtedly, we have a very common example of a micro ring resonator that comes in the samples folder in your installation directory. Using a ring waveguide with a fiber profile the toroid structure can be made in exactly the same way.
    
    Cheers
- April 6, 2015 at 5:49 pm #19309
  
  Noha Anous
  Participant
  
  Dear Damian,
  Thanks for the prism file comaptible with the 32 bits,
  but I have some questions if you please:
  
  1 – To compute the effective index of the structure, shall I choose 2D modal, then when computing the mode, shall I click on the 3 waveguides?? or only the gold to compute the plasmonic mode?
  (When I choose the three waveguide, I do not get a mode)
  
  2- On the other hand, only choosing the gold layer, gives me only 1 symmetrical mode … there is supposed to be another antisymmetrical mode which doesn’t appear even when I increase the no. of modes to be computed!
  
  3 – How is it possible to increase the resolution in the modal solutions?? It is set to 401 points, is it possible I’m not getting the anti-symmetrical mode because of the low resolution?
  
  4- As for the ring example you mentioned earlier, it’s a dielectric ring, is there an example for a plasmonic ring because I’m facing some problems with that?
  
  Thanks a lot in advance.
  
  Noha
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