Design and optimization of zone plates for flying focus applications

TL;DR

This paper introduces a novel zone-plate-based flying focus scheme with sinusoidal modulation, enabling high-intensity, long-range focal regions and tunable speeds, advancing high-intensity laser applications.

Contribution

It proposes a new modulated zone plate design that suppresses high-order foci and extends focal region length, with tunable focal speed exceeding light speed.

Findings

High-order foci suppressed by over two orders of magnitude

Focal region extends over more than 100 Rayleigh lengths

Focal speed tunable beyond the speed of light

Abstract

Flying focus laser pulse technology, characterized by programmable velocity profiles and the ability to break the traditional link between focal spot motion and group velocity constraints, holds significant potential for revolutionary advances in high-intensity laser related fields. However,the flying focus generated with conventional approaches suffers from a low maximum intensity, as the energy is spread over a long distance, and the size of the focusing optics is also limited. Here, we propose a zone-plate-based flying focus scheme in which the zone widths are modulated by a sinusoidal random distribution. Numerical simulations show that the high-order foci produced by the modulated zone plate can be suppressed by more than two orders of magnitude. Meanwhile, the scheme sustains a high-intensity focal region extending over more than 100 Rayleigh lengths. Furthermore, the focal speed can be tuned over a wide range, including values exceeding the speed of light in vacuum. Owing to these advantages, the proposed modulated zone-plate scheme offers new possibilities for high-intensity laser physics and holds promise for applications such as laser wakefield acceleration, photon acceleration, and more.