Abstract
The distant projection of high-peak and average-power laser beams in the atmosphere is a long-standing goal with a wide range of applications. Our early proof-of-principle experiments [Phys. Rev. X 4, 011027 (2014)] presented one solution to this problem, employing the energy deposition of femtosecond filaments in air to sculpt millisecond-lifetime sub-meter-length air waveguides. Here, we demonstrate air waveguiding at the 50-m scale, , making many practical applications now possible. We employ a new method for filament energy deposition: multifilamentation of Laguerre-Gaussian “donut” modes. We first investigate the detailed physics of this scheme over a shorter 8-m in-lab propagation range corresponding to 13 Rayleigh lengths of the guided pulse. We then use these results to demonstrate optical guiding over 45 m in the hallway adjacent to the lab, corresponding to 70 Rayleigh lengths. Injection of a continuous-wave probe beam into these waveguides demonstrates very long lifetimes of tens of milliseconds.
3 More- Received 9 August 2022
- Revised 30 November 2022
- Accepted 7 December 2022
DOI:https://doi.org/10.1103/PhysRevX.13.011006
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Viewpoint
Air Waveguide from “Donut” Laser Beams
Published 23 January 2023
A waveguide sculpted in air with lasers transmits light over a distance of nearly 50 meters, which is 60 times farther than previous air-waveguide schemes.
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Popular Summary
Long-distance projection and collection of optical signals in the atmosphere has long been limited by beam spreading and atmospheric distortion. Beam spreading is a natural consequence of the wave nature of light, while the distorting effects of turbulence, aerosols, and high-power thermal blooming are intrinsic to atmospheric conditions. Here, we demonstrate a new method for forming beam-confining waveguides over very long distances in air that can overcome beam spreading and atmospheric distortion.
Our prior work sculpted air waveguides by heating the air with an ultrashort pulse to guide an injected secondary pulse over 70_cm. In this work, we significantly extend these waveguides by using a new ultrashort “vortex” pulse with a donut-shaped beam profile and demonstrate guiding of an injected secondary pulse over 50_m, almost 2 orders of magnitude longer than in our earlier work.
We show the physics underlying our new method and how the requirements for waveguide generation scale straightforwardly with length, pointing the way to kilometer-length optical air waveguides and beyond.