Nonlinear optics in the angstrom regime:: Hard-x-ray frequency doubling in perfect crystals -: art. no. 041804

Based on the dynamical diffraction theory, we demonstrate the important role of the multiple scattering effects in an x-ray frequency doubling in crystals, generally leading to a generation of two coupled second-harmonic waves propagating in the forward and scattering direction. The possibility to phase match the process is shown for the Laue and Bragg geometry. Modeling of a frequency-doubling experiment suggests that the harmonic signal should be measurable for x-ray pumping with picosecond pulses of mJ energy.