Email office@phys.ksu.edu for the Zoom address
Abstract
Ultrafast laser oscillators are devices that generate trains of femtosecond (1 fs = 10-15 seconds) visible or near-infrared pulses. The working principle is modelocking, a technique based on engineering a dispersion-free laser cavity over a broad spectral range of the gain medium, assuring temporal and spatial integrity of the pulse each roundtrip. Nowadays, modelocked laser oscillators are essential devices in science and technology, from chirped pulse amplification, high precision spectroscopy via frequency combs, ultrafast nonlinear optics applications, laser machining, etc. In this talk, I will present the formation of dispersion-free attosecond photoelectron pulses during multiphoton ionization of atoms and molecules circulating in a nanoscale, mirrorless matter wave cavity analogous of modelocked lasers. With dispersion compensation achieved by balancing the dispersive properties of the Coulomb potential of the ion and the ponderomotive forces of the laser field, I will show how dispersion can be engineered by controlling the chirp and the amplitude of the laser field. Finally, I will demonstrate how these dispersion-free attosecond photoelectron pulses lead explain the formation of high order above threshold ionization enhancements, a phenomenon observed three decades ago in multiphoton ionization.