ABSTRACT
We present a novel method for controlling the transverse positions and relative powers of multiple high-order harmonic beams. A phase-only spatial light modulator is used to produce multiple infrared foci, the positions and intensities of which can be controlled programmably, enabling the generation and control of multiple HHG beams. To demonstrate the utility of this method we perform Fourier transform holography with separate illumination of the object and reference pinhole by a pair of HHG beams, which makes optimal use of the available photon flux. The programmable control of the spatial distribution of HHG beams demonstrated here offers new opportunities for experiments at extreme ultraviolet (XUV) wavelengths, particularly for photon intensive applications such as imaging.
ABSTRACT
Spatially resolved interference is observed between high-order harmonics generated in two longitudinally separated gas targets. High-contrast modulations in the intensity of each harmonic order up to the cutoff are observed on-axis in the far field of the source as the separation between the gas targets is increased. For low-order harmonics, additional off-axis modulations are observed, which are attributed to the interference between the contributions from the long quantum trajectories from each gas target. The inherent synchronization of this setup offers the prospect for high-stability metrology of quantum states with ultrafast temporal resolutions.
