Coherent modulation of intense XUV pulses by ground-state coupling

We present and validate a method to modify the interaction between laser fields and an atomic three-level system based on the control of the ground state, which is interpreted with a direct analytical formula. Coherent modulation of intense extreme Ultraviolet (XUV) pulses is achieved by using near-infrared (NIR) lasers as control pulses interacting with the atomic systems, i.e. quantum transition paths are manipulated in light-matter interactions caused by the laser. We analyze the feasibility of realizing the phase reversal of the dipole response in the three-level system by controlling the interaction between the ground state and another excited state. The discussion of the modulation of intense XUV pulses complements recent studies relying on perturbative excitation. These observations provide new insights for achieving pulse shaping of the XUV frequency range by using the NIR pulse as a control pulse.