Guilin Sun
Ansys Employee

This is a common problem, meaning the optical generation is too large for the current mesh to resolve. Please check the power scale factor and make sure the injected power is proper for the small device. In addition you may need to increase the iteration limit etc. Please refer to

https://optics.ansys.com/hc/en-us/articles/360034918633-CHARGE-solver-Simulation-object