You can already do this, @Catelite I believe has a save in which she demonstrates splitting photons up based on color. I believe it just uses prisms of GLAS and FILT. Then you can just put void in the path of the colors you don't want.

@Shriek (View Post)
so like FILT, but reflects the colours that are not the colour of it. That would make light refracters more realistic.