# Orbital angular momentum of photon

People talk about orbital angular momentum (OAM) of photons. Is there some physical example that cannot be explained without assuming that photons have non-zero OAM? Does different photons have different values of OAM? If yes, then what determines the value of the value orbital angular momentum carried by individual photons?

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You may be correct. But if you are, this leaves open another question that has been on my mind. How can a gamma photon emitted from an $I=2$ or $I=3$ nuclear transition carry away only one $1ℏ$ unit of angular momentum (i.e., its intrinsic spin)? – Eric Walker Oct 29 '15 at 5:11