Ultra-Short flying-focus

TL;DR

This paper introduces a theoretical model and compensation technique for ultrashort pulses in achromatic flying-focus systems, enabling precise control of pulse duration and velocity, with potential applications in ultrafast optics and plasma interactions.

Contribution

It presents a novel spectral chirp compensation method to counteract pulse elongation caused by spatiotemporal coupling in flying-focus systems.

Findings

Spectral chirp compensation preserves pulse duration.

Numerical simulations confirm velocity control over extended regions.

Dispersive media can naturally reduce pulse elongation.

Abstract

Achromatic flying-focus enables programmable control of intensity peak velocity, with applications in ultrafast optics. However, spatiotemporal coupling inherently elongates ultrashort pulses by introducing frequency-dependent focusing and arrival-time dispersion. We present a theoretical model identifying this pulse-lengthening effect and propose a radially-dependent spectral chirp to compensate for chromatic timing mismatches. Numerical simulations confirm that this approach preserves both pulse duration and programmed flying-focus velocity over extended focal regions. Additionally, dispersive media such as plasmas can naturally mitigate elongation. These results extend achromatic flying-focus techniques to ultrashort pulses, enabling new opportunities in laser--plasma interactions and high-field nonlinear optics.