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I shone a green laser light(~532 nm) through a glass slab and what I saw inside was that the light beam was now red. Imagine a regular refraction diagram but color the beam outside green and that on the inside red.

As frequency doesn't change upon entering another medium, effective light velocity in a medium becomes directly proportional to that of wavelength. So, as speed decreases shouldn't wavelength also do so? But in this case, it increases. Or is this logic wrong?

Also, it can't be due to light losing energy.

What is happening in here?

Qmechanic
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Adam Karlson
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I also noticed this happening, also with a 532nm green laser, but the beam inside was somewhat more orange than red. This only happened with one particular piece of glass that I had, the sphere from this set: https://www.amazon.com/dp/B08CZ9PCJP/?ref_=cm_wl_huc_item It is advertised as "k9 material", and other than this color change, I have no reason to believe it is a different material. it may be due to the shape, but changing the angle of incidence does not change the color. I tried to shine through different types of glass laying around my house, and water too, and I found one particular whiskey glass that does a similar (but far less noticeable) color change. After further reading, it seems to be raman scattering, a type of fluorescence, and is usually due to Ge impurities in the glass.

Garmysheva, T.Y., Shendrik, R.Y., Paklin, A.S. et al. Luminescence of Oxygen-Deficient Centers in Quartz Glasses. Glass Phys Chem 48, 232–235 (2022). https://doi.org/10.1134/S1087659622030038

Jason Killian
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