Phase Shifts and Interference in Reflection: Understanding the Differences

[condorino]

Hi all!

I have a problem about the phase shift an e.m. wave acquire when, traveling through air, it's reflected back by a mirror (or a beam splitter) with n > n(air).

Now, I know the example of the thin film interference due to a π shift of the wave reflected by the medium.

But I see that in the Mach-Zender interferometer (for photons), when the two paths are different for the presence of two additonal reflections (on the beam splitters), we obtain a destructive interference (meaning a π phase shift). So it seems that each reflection on a beam splitter produces a π/2 phase shift, instead of a π phase shift.

So the thin film interference and the Mach-Zender interference have something different.

Now the question is:

Is that due to a feature (that I'm not able to find) of the beam splitters or is that a consequence of the different angle of incidence of light on the beam splitters (π/4 instead of π/2)??

Thx

 

[Charles Link]

This is kind of difficult to follow, but suggest you read through the following thread: https://www.physicsforums.com/threads/if-maxwells-equations-are-linear.969743/