I have an optical setup where monochromatic light (573.5nm) is passed through a cuprous oxide crystal (Cu2O). This light is then passed through a monochromator, but the output light is actually polychromatic (the spectra looks like the components of white light). Could someone please explain how this works? To me it seems baffling that polychromatic light could be reproduced this way.
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1$\begingroup$ Can you provide some additional information, i.e., the wavelength of the incident light and the spectrum of the polychromatic light? $\endgroup$– Ed VCommented Mar 30, 2022 at 2:19
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$\begingroup$ The wavelength of the incident light is 573.5 nm, the polychromatic light is just the components of white light, from 400nm to 700nm. $\endgroup$– HoratioCommented Mar 30, 2022 at 2:20
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1$\begingroup$ I suspect you'll want to look up the nonlinear properties of your $Cu_20$ crystal. $\endgroup$– Carl WitthoftCommented Mar 30, 2022 at 15:38
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1 Answer
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Since the light changes its wavelength after passing through the crystal, one must conclude that the photons of the light are absorbed by the atomic structures of the crystal and then re-emitted.
If you have a monocrystal, the prediction is that the spectrum even changes depending on the angle of incidence of the monochromatic beam.
This all has to do with the fact that the absorbed energies in the atomic structures are not re-emitted 100 percent, but also lead to displacements and vibration changes in the crystal in intermediate processes. In addition, as in every process of energy conversion, part of the energy is converted into low-frequency (infrared) radiation. The crystal heats up.
It is predicted that the heating of the crystal leads to a further change in the re-emitting spectrum.
answered Mar 31, 2022 at 3:43