Guilin Sun
Ansys Employee

Yes, this is normal, since when the wavelength changes, the material fitting changes and thus it affects the refractive index used, and possibly the mesh size (the automesh background).

Please refer to this post: 

Ansys Insight: 光谱宽度会影响同波长的透过率吗?分段仿真如何得到光滑的结果