Long-distance axial spectral encoding using space-time wave packets

TL;DR

This paper demonstrates long-distance axial spectral encoding using space-time wave packets, enabling spectral changes over hundreds of meters for potential applications in LIDAR and sensing.

Contribution

It introduces and experimentally verifies axial spectral encoding in space-time wave packets over long distances, a novel propagation configuration for optical beams.

Findings

Spectral shifts observed over hundreds of meters in open-field laser range.

Two configurations demonstrated: spectrum shifts with distance and parameter-controlled spectrum changes.

Potential for spectral measurements to be used in LIDAR and sensing applications.

Abstract

Space-time wave packets (STWPs) are pulsed optical beams whose spatiotemporal structure enables propagation invariance. However, STWPs allow for a unique propagation configuration that we call axial spectral encoding, in which the spectrum on the propagation axis changes with distance. We demonstrate here axial spectral encoding over distances extending for hundreds of meters in an open-field laser range. We verify two distinct configurations: in the first, the on-axis spectrum blue-shifts or red-shifts with propagation distance; and in the second, the spectrum changes at a fixed axial position by altering an internal parameter of the STWP without modifying the wave packet spectrum. These results indicates the potential for using spectral measurements for ranging in LIDAR and sensing applications.