Tailoring the spatio-temporal distribution of diffractive focused ultrashort pulses through pulse shaping

TL;DR

This study demonstrates how pulse shaping can precisely control the spatio-temporal distribution and propagation characteristics of ultrashort laser pulses near focus, with detailed analysis of spectral phase effects.

Contribution

It introduces a method to manipulate ultrashort pulse focusing and propagation through spectral phase shaping, supported by experimental and simulation data.

Findings

Pulse shaping modifies the spatio-temporal irradiance distribution.

Spectral phase components influence propagation and frequency distribution.

Second and third order dispersion effects show distinct symmetries and behaviors.

Abstract

Focusing control of ultrashort pulsed beams is an important research topic, due to its impact to subsequent interaction with matter. In this work, we study the propagation near the focus of ultrashort laser pulses of ~25 fs duration under diffractive focusing. We perform the spatio-spectral and spatio-temporal measurements of their amplitude and phase, complemented by the corresponding simulations. With them, we demonstrate that pulse shaping allows modifying in a controlled way not only the spatio-temporal distribution of the light irradiance in the focal region, but also the way it propagates as well as the frequency distribution within the pulse (temporal chirp). To gain a further intuitive insight, the role of diverse added spectral phase components is analyzed, showing the symmetries that arise for each case. In particular, we compare the effects, similarities and differences of the second and third order dispersion cases.