Temporal and spectral control of the X-ray pulses in a resonant medium with a modulated transition frequency

Abstract

We discuss a method for controlling the spectral and temporal characteristics of X-ray radiation produced by a radioactive or synchrotron MÓ§ssbauer source via its propagation through an optically thick sample of resonant nuclei with a modulated transition frequency. Such modulation is achieved via a Doppler frequency shift due to vibration of the recoilless absorber. We show that this technique can be used both for effective elimination of the resonant absorption (acoustically induced transparency) and temporal shaping of an individual photon, including the production of short pulses. A similar technique can be used for formation and amplification of attosecond pulses in the active medium of a plasma-based X-ray laser, where the resonant transition frequency of ions is modulated by a sufficiently strong infrared field.