I've read a handful of book by or about Levinas, but some time ago and without notes. IIRC his central ethical theme is that other people are not an aspect of the self, that our obligation to them exists in their being irreducible to ourselves.
E.g. you have this by Zahavi
i.e. that alterity is originarily an ethical relation, so that its call to conscience is more important that any aspect of comprehension: and so (it seems to me) independent of how we seem to exist as individuals.
Against these enigmas, every mode of comprehension runs aground.... The other person is an event I can neither predict nor control.
Assuming that is a fair definition of "radical alterity", I wondered if there has been any attempt to apply a similar concept to aesthetics (rather than its usual place of obligation).