This kind of mirrors exist for only a fragment of time but could help to reduce the size of ultrahigh power lasers, which currently occupy buildings the size of aircraft hangars, to university basement sizes. They have potential to be developed into a variety of plasma-based, high damage-threshold optical elements that could lead to small footprint, ultrahigh power, ultrashort pulse laser systems. The new way of producing mirrors, and other optical components, points the way to developing the next genera­tion high power lasers, from hundreds of petawatts to exawatts. 

Dino Jaroszynski of of Strathclyde’s physics department led the research. He said: “Making high power lasers more widely available would transform the way science is done; a university could have these tools in a single room, on a table top, for a reasonable price. This work signi­ficantly advances the state-of-the-art of highpower lasers by proposing new methods for creating optical elements, which are more robust than existing elements and also transient, which makes them unique.”

“This is more compact and much more robust and could provide a paradigm shift in high power lasers, which would stimulate new directions of research. The new method presented would also be of wide interest to a diverse community developing and using high power lasers. The group is now planning further proof-of-principle experiments to demonstrate the robustness and fidelity of the plasma optical elements,” Jaroszynski said.

The new research has produced layered plasma mirrors using counter-propa­gating laser beams. Counter-propagating laser beams produce a beat wave in plasma that drives electrons and ions into a regular layered structure, which acts as a very robust, high reflec­tivity mirror. This mirror exists only fleetingly, for a few picoseconds and its ghostly presence enables very intense laser light to be reflected or mani­pulated.  

The transient layered plasma is a volume Bragg grating, similar to Bragg structures found in crystals, and is only a few millimeters across. It has the potential to be developed into a variety of plasma based, high damage-threshold optical elements that could lead to small footprint, ultrahigh power, ultrashort pulse laser systems. Gregory Vieux, who designed and undertook the experiments, said: “This new way of producing transient robust plasma mirrors could revo­lutionize acce­lerators and light sources, as it would make them very compact and capable of producing ultrashort duration ultraintense pulses of light, that are much shorter than can be produced easily by any other means.”

“Plasma can withstand inten­sities up to 10¹⁸ watts per square centimeter, which exceeds the threshold for damage of conventional optics by four or five orders of magnitude. This will allow the size of optical elements to be reduced by two or three orders of magnitude, shrinking meter-sized optics to millimeters or centi­meters,” he said. (Source: U. Strathclyde)

Reference: G. Vieux et al.: The role of transient plasma photonic structures in plasma-based amplifiers, Commun. Phys. 6, 9 (2023); DOI: 10.1038/s42005-022-01109-5

Link: Scottish Centre for the Application of Plasma-based Accelerators, University of Strathclyde, Glasgow, UK