Ultrafast manipulation of hard x-rays by efficient Bragg switches

We experimentally demonstrate efficient switching of the hard x-ray Bragg reflectivity of a SrRuO3/SrTiO3 superlattice by optical excitation of large-amplitude coherent acoustic superlattice phonons. The rocking curve changes drastically on a 1 ps timescale. The (0 0 116) reflection is almost extinguished (ΔR/R0=−0.91), while the (0 0 118) reflection increases by more than an order of magnitude (ΔR/R0=24.1). The change of the x-ray structure factor depends nonlinearly on the phonon amplitude, allowing manipulation of the x-ray response on a timescale considerably shorter than the phonon period. Numerical simulations for a superlattice with slightly changed geometry and realistic parameters predict a switching-contrast ratio ΔR/R0 of 700 with high reflectivity.