Googling dielectric mirror phase shows up several citations for a pi phase shift (though I think those were all 100% reflectance mirrors). A good citation for a pi/2 phase shift seems to be here, though I haven’t actually double-checked it.
Googling dielectric mirror phase shows up several citations for a pi phase shift (though I think those were all 100% reflectance mirrors). A good citation for a pi/2 phase shift seems to be here, though I haven’t actually double-checked it.