Alternative explanation of specular optical activity

Bungay et al. [Phys. Lett. A 174, 335 (1993)] reported observing polarization plane rotation in optical reflection at normal incidence from GaAs, an effect that they term specular optical activity. Their preferred interpretation hypothesizes a partially symmetric third-rank bulk tensor arising from nonlocality, even though its existence would violate time reversibility. We present an alternative explanation based on the derived properties of a nonlocal surface layer that preserves time reversibility.