Hi,

What do you want to do by truncating the computational domain?

What is your goal?

you can change the geometry of the waveguide using parametric sweep by defining specific parameter and ask parametric sweep to vary between the range you define for it.

Dear @Parviz Saeidi,

I am trying to calculate the total decay rate of a quantum emitter near a cylindrical waveguide sitting on a substrate (cubic shaped). It is well known to truncate such domain, a pml layers with half wavelength thickness should be on the transversal plane and along the longitudinal direction, we should use mode matching boundary conditions (I used scattering boundary conditions to absorb the EM field). However, for such a domain, the COMSOL solver does not converge, it took too much time with high error. However, if I simulate only the quantum emitter near a cylindrical wire embedded in a dielectric with cylindrical truncation, the system operates in no time. How can I perform a proper truncation for the aforementioned structure?

thank you for your reply.

Yours sincerely,

Farooq Abdulghafoor Khaleel

I am not expert in the structure you told. however, two suggestion came to my mind:

1- one way could be designing your structure without PML and use only the scattering boundary condition to absorb outgoing waves and then truncate your domain.

2- the best way is to send an email to the COMSOL supporter and ask the technician to help you. they have always useful suggestions and information.

Dear Parviz Saeidi

I did the first suggestion (It was one of 1000 try). However, the solver still cant converge to a solution.

Thank you for your reply.

I am still looking for other solutions.

Yours,