Record-breaking all-silica metasurfaces from INESC MN researchers promise a new era of high-power lasers.

Researchers at INESC MN and Instituto Superior Técnico have carved glass skyscrapers only a few hundred nanometers wide but more than three micrometers tall, creating the highest-aspect-ratio flat-optics ever reported. The monolithic silica devices—known as metasurfaces—endow high-intensity laser beams with tailor-made phase and polarization profiles, capabilities extremely precious at high power levels for fusion research, particle acceleration and bright X-ray generation. The work was published in Optica.

“From day one we knew success meant staying monolithic,” says senior author Prof. Marco Piccardo of Tecnico Lisboa and INESC MN. “We are literally sculpting nanostructures out of the original block of glass—like Michelangelo did in marble but at the nanoscale—so the optics remain nearly as robust as bulk fused silica.”

Traditional metasurfaces consist of high-index nanostructures sitting on a different substrate. The buried interface is a weak link when peak intensities climb. By etching the patterns directly into fused-silica wafers—using a developed mask and etch recipe—the team produced tall pillars with a slender 14:1 aspect ratio, a significant leap over previous metasurface work. The tall pillars enhance the interaction in low-index silica unlocking the full phase tunability demanded for advanced beam shaping.

In laboratory tests the metasurfaces shaped femtosecond Ti:sapphire pulses to donut-shaped vortex beams while withstanding power densities within a factor of five of bare glass—orders of magnitude tougher than hybrid devices. Scaling the optics size to the centimeter scale promises extreme on-target intensities, enabling relativistic charged-particle beams, novel radiation sources and eventually progress on laser-fusion drivers.

“Up to now, intense laser facilities relied primarily on conventional optics,” Piccardo notes. “Our flat-optics platform folds tremendous new functionality into a wafer-thin element.” Prof. Piccardo is also publishing a topical review on structured laser–matter interactions in Optica with worldwide experts in the field, mapping out how such devices could transform everything from tabletop setups to high-intensity flagship lasers.

The research was supported by the European Research Council (ERC), Fundação para a Ciência e a Tecnologia (FCT), and the European Innovation Council (EIC). Co-authors include Beatriz Oliveira, Pablo San Miguel Claveria, Pedro Araujo, Patrícia Estrela, Ines Gonçalves, Maria Inês Nunes, Rui Meirinho and Marta Fajardo.

The link to the paper can be found here

Prof. Piccardo is also publishing a topical review on structured laser–matter interactions in Optica with worldwide experts in the field.

Contact: Prof. Marco Piccardo, Instituto Superior Técnico / INESC MN