Spin-orbit coupling in vortex light: can it be revealed in fundamental electronic transitions?

摘要

Recent theoretical work on circular dichroic effects, for absorption processes in chiral materials, has reopened questions over the possibility that the interactions of vortex beams may display a sensitivity to material handedness. The interest in such a phenomenon arises from the fact that any engagement of optical phase gradients, in quadrupole-allowed electronic transitions, will represent a distinctive form of engagement with chiral matter. This is an issue that numerous careful experiments have so far failed to fully resolve, with some of them giving a clear null result, yet others giving positive indications. A definitive outcome from any such investigation would represent a touchstone for a broader, yet more challenging question: is there any mechanism by means of which twisted light, which conveys both orbital and spin angular momentum, can exhibit coupling between the two? It emerges that such a possibility can be identified, but the constraints upon its manifestation are severe. This presentation sets out the principles and the conclusions to which they lead, informing the pathway for ongoing experimentation.