Learning Forum

[Guilin Sun]

I am sorry to hear this.

First, please check if the source mode is correctly selected. When metal appears the mode source may not be able to automatically find the correct mode.  You may specify "near n" with value of the neff when there is no metal material.

Once the source mode is correct, please check imag(neff) or loss to see if it is too large. Attaching metal close to waveguide core can have very large loss such that the mode may propagate very short distance.  If this happens, please first move the metal away from the waveguide, check the mode and its loss. then gradually move down the metal and see when the loss is too large to propagate.

Please post some screenshots so I can understand your structure and settings easily.