Skip to main content Skip to secondary navigation

Strong-field Physics

Main content start

We study the fundamental response of solid materials, atomic and molecular gases, as well as the vacuum to intense and super intense laser fields. Strong-field nominally refers to the low-frequency optical laser, where the strength of the laser field approaches or exceeds the interatomic binding strengths in crystals or molecules, which are on the order of volt per angstrom. This is the regime of non-perturbative laser-matter interaction, which includes nonlinear optical phenomena such as high-order harmonic generation (HHG) and above-threshold ionization (ATI). Such experiments are typically in table-top forms in PULSE laser laboratories. With the advent of modern x-ray free-electron lasers such as the LCLS, intense laser fields are now available in the x-ray wavelength range as well. In such a high-frequency regime, we study nonlinear multi-photon processes such as sequential and non-sequential x-ray absorption, nonlinear Compton scattering, and X-ray optical wave-mixing processes. Often, we perform pump-probe experiments, where the pump pulse initiates a novel ultrafast dynamics in materials and the probe pulse takes snap-shots of such rapidly evolving dynamics.