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- Is the phase shift 90 or 180 degree on reflection?
I'm confused by the phase shifts in a Mach-Zehnder interferometer because I keep finding two different explanations.
One explanation (for example, given on Wikipedia, but also elsewhere) states that on each reflection, the phase shift is 180 degrees, but only, if light is reflected from the front of a beam-splitter but not from the back. In this explanation, the second beam splitter is reversed (as shown on the Wiki page).
However, there are other explanations like this given here:
https://chem.libretexts.org/Bookshe...m_Computer_with_a_Mach-Zehnder_Interferometerwhere it is stated that each reflection has a 90-degree phase shift.
Both explanations work (in the sense that they both give the correct result for constructive/destructive interference), but which one is correct? Or are they both correct because it is also possible to construct mirrors with 90-degree phase shifts (for example, by choosing the correct path length in a dielectric and putting the mirror surface always at the back)?
Thanks for any help.
One explanation (for example, given on Wikipedia, but also elsewhere) states that on each reflection, the phase shift is 180 degrees, but only, if light is reflected from the front of a beam-splitter but not from the back. In this explanation, the second beam splitter is reversed (as shown on the Wiki page).
However, there are other explanations like this given here:
https://chem.libretexts.org/Bookshe...m_Computer_with_a_Mach-Zehnder_Interferometerwhere it is stated that each reflection has a 90-degree phase shift.
Both explanations work (in the sense that they both give the correct result for constructive/destructive interference), but which one is correct? Or are they both correct because it is also possible to construct mirrors with 90-degree phase shifts (for example, by choosing the correct path length in a dielectric and putting the mirror surface always at the back)?
Thanks for any help.