FIG. 3.

Dynamical phases in a two-crystal geometry. (a) Momentum-space depiction, with the component of k along H selected by the crystal colored. The magnitude of the crystal’s angular acceptance relative to the spread of the wave packet in phase space is greatly exaggerated for clarity. (b) Coherent recombination is dependent on the precise alignment of the crystals and a uniform potential between and within the diffracting crystals. Only the infrared deviations from Bragg are shown; the ultraviolet deviations follow the same pattern.