Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

RF Module - Waveguides with arbitrary cross sections: numeric ports setting

Please login with a confirmed email address before reporting spam

Hi to everyone,

I'm new to Comsol Multiphysics, and I'm trying to simulate some waveguides with arbitrary cross-sections. My problem is that it isn't clear to me the meaning of the numeric settings port, in particular:

"Desired number of modes"
"Search for modes around"

I didn't find a clear answer in the Comsol help or in the model examples. Could someone tell me the physical meaning of this two settings?

Thanks!

Bye

1 Reply Last Post 18 nov. 2011, 16:31 UTC−5

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 18 nov. 2011, 16:31 UTC−5
"Desired number of modes" is just the number of eignmodes to solve for. For example, if you were only interested in the fundamental mode or you know you had a single-mode waveguide, then you would set this parameter to 1.

"Search for modes around" is like an initial guess. If you're working with effective mode indices, then COMSOL will begin it's search around/below the refractive index you enter here. For example, if you're modeling a silica fiber with an air cladding, then I'd enter 1.4. I think there is a choice with what eigenvalue you can enter here -- mode index, propagation constant, etc. Just make sure that you enter in the right number for whatever eigenvalue you choose!
"Desired number of modes" is just the number of eignmodes to solve for. For example, if you were only interested in the fundamental mode or you know you had a single-mode waveguide, then you would set this parameter to 1. "Search for modes around" is like an initial guess. If you're working with effective mode indices, then COMSOL will begin it's search around/below the refractive index you enter here. For example, if you're modeling a silica fiber with an air cladding, then I'd enter 1.4. I think there is a choice with what eigenvalue you can enter here -- mode index, propagation constant, etc. Just make sure that you enter in the right number for whatever eigenvalue you choose!

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.