Discussion Forum

Hi,

I am using the RF module of COMSOL 4.3b to determine the effective refractive index of the modes of a waveguide as a function of the wavelength (for instance between 600 and 700 nm). I am therefore using the parametric sweep in wavelength and then run the mode analysis to have the effective index for each wavelength.

For the fundamental mode it works well. I first do a modal analysis for the initial wavelength to determine the initial effective index and be able to complete the "search for modes around". Then I run the modal analysis and the effective indices in all the wavelength range correspond to the fundamental mode.

So this method works for the fundamental mode because its effective index varies quite slowly with the wavelength and all the results are still around the initial "search for modes around". However I have some troubles with the first order mode, if I do a parameter sweep of more than 5 nm the resulting effective index are not the ones of the first order mode anymore. And this is because of the condition "search for modes around" that limits the result around this value and prevent the software to look for lower indices.

So my question is: can I add a condition on the mode solver when doing wavelength sweep? For instance instead of always having the same value for "search for modes around", would it be possible to make the software use the last effective index obtained as a starting point for the next calculation?
Or to add a condition on the consecutive results such as neff (i+1) < neff (i)?

Thank you!