Reply To: How to understand the loss in MODE Eigensolver analysis mode list

[Amrita Pati]

Hi Leroy,

Thanks for sharing the screenshot! This looks like silica. Are you using silica in the core, any chance this is the cladding? If any other material is used in the core then you can look at its fit by choosing this material from the "Material" drop-down menu. From this fitting it looks like the imaginary part of the refractive index is close to 0, so I won't expect a lot of losses unless you are simulating a bent waveguide. If you see that material properties of the core material (values reported in literature) are different than the values in the material database, you can try using the "Object Defined Dielectric" and then set the value of n (both real and imaginary) from other sources. The 2nd thing you can do is perform convergence testing to make sure that the values of losses reported by the solver are accurate. This is to make sure that the losses reported by the solver are not impacted by the PML boundaries. So, we run multiple simualtions (could use the sweep utility) increasing the simulation span to minimize modal interactions with PML as much as possible. If you keep increasing the simulation span, the losses should converge beyond a certain point and this should be the accurate loss value.

Regards,
Amrita