SIMULATING STRONG FIELD RESCATTERING USING ATTOSECOND LIGHT

An atom or molecule interacting with an intense, ultrafast laser pulse is a fundamental problem in modern physics. At intensities that are approximately one-tenth an atomic unit of field (50 V/A) the physics is well described by a semi-classical 3-step model where an electron tunnel ionizes, driven by the strong-field and then rescatters with its parent core. The consequence of this physics has opened the areas of attosecond science and spatial-temporal molecular imaging. However in a strong field experiment, the exponential rate of tunnel ionization fixes the release phase of the electron wave packet (EWP) at the extreme of the laser field. In this talk, we will describe a method that allows for more precise studies of the strong field process. The approach simulates the 3-step model by replacing the tunneling step with single-photon ionization by an attosecond XUV pulse. A phase-locked intense low-frequency field drives the EWP mimicking steps (2) and (3) but with little or no ionization. We will present both experimental and theoretical results demonstrating the viability of this approach

High-energy mid-infrared sub-cycle pulse synthesis from a parametric amplifier

High-energy phase-stable sub-cycle mid-infrared pulses can provide unique opportunities to explore phase-sensitive strong-field light-matter interactions in atoms, molecules and solids. At the mid-infrared wavelength, the Keldysh parameter could be much smaller than unity even at relatively modest laser intensities, enabling the study of the strong-field sub-cycle electron dynamics in solids without damage. Here we report a high-energy sub-cycle pulse synthesiser based on a mid-infrared optical parametric amplifier and its application to high-harmonic generation in solids. The signal and idler combined spectrum spans from 2.5 to 9.0 μm. We coherently synthesise the passively carrier-envelope phase-stable signal and idler pulses to generate 33 μJ, 0.88-cycle, multi-gigawatt pulses centred at ~4.2 μm, which is further energy scalable. The mid-infrared sub-cycle pulse is used for driving high-harmonic generation in thin silicon samples, producing harmonics up to ~19th order with a continuous spectral coverage due to the isolated emission by the sub-cycle driver

19th International Conference on Ultrafast Phenomena

This book presents the latest advances in ultrafast science, including both ultrafast optical technology and the study of ultrafast phenomena. It covers picosecond, femtosecond, and attosecond processes relevant to applications in physics, chemistry, biology, and engineering. Ultrafast technology has a profound impact in a wide range of applications, amongst them biomedical imaging, chemical dynamics, frequency standards, material processing, and ultrahigh-speed communications. This book summarizes the results presented at the 19th International Conference on Ultrafast Phenomena and provides an up-to-date view of this important and rapidly advancing field

High relative-phase precision beam duplicator for mid-infrared femtosecond pulses

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