  Motivated by recent terahertz absorption measurements in $\alpha$-RuCl$_3$,
we develop a theory for the electromagnetic absorption of materials described
by the Kitaev model on the honeycomb lattice. We derive a mechanism for the
polarization operator at second order in the nearest-neighbor hopping
Hamiltonian. Using the exact results of the Kitaev honeycomb model, we then
calculate the polarization dynamical correlation function corresponding to
electric dipole transitions, in addition to the spin dynamical correlation
function corresponding to magnetic dipole transitions.
