Attosecond Pulses: The Three-Step Model of High-Harmonic Generation

This simulator visualises the physical mechanism behind the 2023 Nobel Prize in Physics: an intense laser field tunnel-ionises an atom, classically accelerates the freed electron back and forth, and — when the electron recombines with its parent ion — releases the energy it gained as a single attosecond burst of extreme-ultraviolet light. Adjust the driving laser's peak field and wavelength, pick a target gas to set its ionization potential, and drag the birth-phase slider to explore how the emission energy depends on exactly when, within the optical cycle, the electron tunnels free — while live readouts track the ponderomotive energy, the returning electron's kinetic energy, and the famous I_p + 3.17·U_p harmonic cutoff law that sets the shortest attosecond pulses reachable at a given intensity.