Guilin Sun
Ansys Employee

Are you using Port to calculate the bending loss?  Port only gives you the mode loss due to bending of the waveguide where the port is located. If you have FDE please use the more dedicated solver for mode analysis. Mode in FDTD port is for source excitation and  mode expansion.

The higher loss may mean the mode is penetrating down to silicon. Please check the mode profile and make sure the mode is confined in the waveguide and it is the proper mode you desire.