  We show that the momentum of light can be reversed via the atomic coherence
created by another light with one or two orders of magnitude lower frequency.
Both the backward retrieval of single photons from a timed Dicke state and the
reflection of continuous waves by high-order photonic band gaps are analysed.
The required control field strength scales linearly with the nonlinearity
order, which is explained by the dynamics of superradiance lattices.
Experiments are proposed with $^{85}$Rb atoms and Be$^{2+}$ ions. This holds
promise for light-controllable X-ray reflectors.
