The eigenvalue transform is not supported

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Hi, everyone Sorry to bother you a few moment. Hi, everyone Sorry to bother you a few moment. # I got a problem that's "The eigenvalue transform for Mode analysis is not supported by all physics it solves for - Physics: Solid Mechanics (solid)" I want to build a model to simulate a relationship between optical mode and thermal expansion of geometry; In other words, I want to know if a special fiber like photonic crystal fiber thermal expanded when changing temperature whether transmission mode would be influence.
In step2: Mode Analysis under Study, I choose both solid mechanics and EM wave, then I compute the model. Here comes the problem about "The eigenvalue transform for Mode analysis is not supported by all physics it solves for - Physics: Solid Mechanics (solid)" Do anyone know how to fix this question? or could give me a similar example?

Many Thanks...

Yi-Lin Yu


1 Reply Last Post Oct 10, 2019, 3:01 AM EDT
Ulf Olin COMSOL Employee

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Posted: 1 month ago Oct 10, 2019, 3:01 AM EDT

Hi Yi-Lin,

It is only the EM interface that supports the Effective mode index Transform in the Mode Analysis Study Settings. However, both Solid Mechanics and the EM interfaces support the Out-of-plane wave number Transform. Thus, use Out-of-plane wave number, if you want to include both physics interfaces in the Mode Analysis study step.

If you initially considered solving for effective mode indices around the value , when you use the Out-of-plane wave number Transform, set Search for modes around to . This will solve for modes propagating in the out-of-plane direction with propagation constants around , where is the vacuum wavelength.

Hi Yi-Lin, It is only the EM interface that supports the **Effective mode index** **Transform** in the **Mode Analysis Study Settings**. However, both Solid Mechanics and the EM interfaces support the **Out-of-plane wave number Transform**. Thus, use **Out-of-plane wave number**, if you want to include both physics interfaces in the Mode Analysis study step. If you initially considered solving for effective mode indices around the value \tt{neff}, when you use the **Out-of-plane wave number Transform**, set **Search for modes around** to \tt{neff*ewfd.k0}. This will solve for modes propagating in the out-of-plane direction with propagation constants around 2\pi\times\tt{neff}/\lambda, where \lambda is the vacuum wavelength.

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