A novel, band‐inverted semiconductor junction is proposed. The heterojunction consists of two column V semimetals that have undergone a semimetal‐semiconductor transition, i.e., a thin Bi film of thickness ∼100 A˚ and a Bi1−xSbxalloy with 0.06<x<0.3. Such a junction will support the recently predicted interfacial states. Results of calculations on the dispersion relation and optical transitions pertaining to the interfacial states are presented. It is shown that the optical transition rate between an interfacial state and the conduction state is comparable to that of a conduction‐valence band transition. It is also shown that the optical transitions have very interesting polarization dependences.