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Syntax to invoke solutions at a specific frequency in the frequency domain interface
Posted Sep 29, 2016, 9:37 a.m. EDT Parameters, Variables, & Functions Version 4.4 4 Replies
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in short: When multiple frequencies are solved for in the frequency domain, what is the syntax to invoke the solution at a specific frequency?
In detail: I am modelling a nonlinear optical process enhanced by a nanoparticle, see model attached. I use the wave optics module with frequency domain interfaces. In a first study step, I compute separately the field distribution created by two laser beams at the frequencies f_pump and f_stokes respectively. I can visualize both of them and they seem correct. Those two fields induce a nonlinear excitation, and the resultant field distribution is calculated in the second study step. I introduce the excitation through an external current density node. I would like to write there something like (the actual physical expression is more complicated) chi3*exc.Ex(f_pump)^2*exc.Ex(f_stokes), but I couldn't figure out what is the syntax to invoke the solution at a specified frequency. However, it should be possible, since the two fields can be visualized separately. Or am I missing something on how the solver works and should I structure the model differently?
Of course, any general comment on the model is appreciated as well
Thanks in advance,
Attilio
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I believe you may be looking for the "with" operator. See Reference Manual for COMSOL Multiphysics, version 5.2a, page 250.
Best,
Jeff
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I think your suggestion goes in the right direction, still I cannot make it work yet.
I have modified my simplified expression (see attached model):
"chi3*exc.Ex(f_pump)^2*exc.Ex(f_stokes)" into "chi3*with(1,exc.Ex)^2*with(2,exc.Ex)"
but this results into the Error "The solution specification is nonscalar or out of range".
Interestingly, only the call "with(2,exc.Ex)" triggers the error. However, I can plot both solution 1 and 2 when postprocessing.
Possibly this is because the with operator can be used for result evaluation only, but not in calculations? If so, can you suggest an alternative to access the solutions during calculation? Note I have still version 4.4 at the moment.
Any help of course much appreciated.
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Best regards,
Jeff
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This seems to have solved the problem. However, does this means the "with" operator can be used for calculations as well, and not only in postprocessing?
Best
Attilio
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