The spin of the photon -- a weird experiment with a laser

[donavi]

Hello everybody, I'm playing with a ne -ne laser
And i conducted an interesting experiment
I did colliding beams the type of interferometer Fabry Pero
between the mirrors I put the cuvette with different substances
I tried to detect changes of polarization of the laser beam with the help of a spectral analyzer
and I noticed that the spectrum is slightly different and depending on the what substances in the cuvette i pour.

I want to understand at a fundamental level what happen with the polarization of the laser beam passing through a cuvette with a different substance?

and what happens with the spin of a photon which hit on the molecule or atoms of the substance in cuvette
and what happens when the spin of the photon many times that he passes through closed loops of the two mirrors?

it is not entirely clear what information is logged spectrum analyzer.
in my understanding, is logged just the motion of molecules in a substance in the cuvette
and two mirrors is just the amplifier to record the movement of molecules in the cuvette
but why change the polarization depending on the different substances, i see it is a dynamic process

 

[azntoon]

and it is not clear to me.The answer to these questions lies in the quantum mechanical properties of light. When a photon interacts with a molecule or atom, its spin can be changed. This change in spin can lead to changes in the polarization of the incident photon. The changes in polarization depend on the type of molecule or atom that the photon interacts with. Furthermore, when the photon passes through closed loops between the two mirrors, it can experience interference effects which can also affect its polarization. Finally, the spectrum analyzer records changes in the intensity of the different components of the polarized light, which can reveal the changes in polarization.