Researchers have created the world's first pure glass laser

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By Matthew Griffin Industrial Revolution 18th April 2024

WHY THIS MATTERS IN BRIEF

By creating a laser out of pure glass future lasers can be much smaller, simplified, and be much more stable and reliable and has lots of future applications.

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Is it possible to create a Femtosecond laser entirely from glass? That’s the rabbit hole that Yves Bellouard, head of EPFL’s Galatea Laboratory, went down after years of spending hours and hours and hours aligning femtosecond lasers for lab experiments. The Galatea laboratory stands at the intersection of optics, mechanics, and materials science, with femtosecond lasers being a key element of Bellouard’s work. These lasers emit extremely short and consistent bursts of light and have applications in various fields such as helping create real holograms, laser eye surgery, non-linear microscopy, spectroscopy, and even sustainable data storage. Typically, commercial femtosecond lasers are constructed by mounting optical components on a substrate, like optical breadboards, necessitating meticulous alignment.

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“We use femtosecond lasers for our research on the non-linear properties of materials and how materials can be modified in their volume,” explains Bellouard. “Going through the exercise of painful complex optical alignments makes you dream of simpler and more reliable ways to align complex optics.”

Bellouard and his team’s solution? Use a commercial femtosecond laser to make a femtosecond laser out of glass, no bigger than the size of a credit card, and with less alignment hassles. The results are published in the journal Optica.

To make a femtosecond laser using a glass substrate, the scientists started with a sheet of glass.

“We want to make stable lasers, so we use glass because it has a lower thermal expansion than conventional substrates, it is a stable material and transparent for the laser light we use,” Bellouard explains.

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Using a commercial femtosecond laser, the scientists etch out special grooves in the glass that allow for the precise placement of the essential components of their laser. Even at micron-level precision fabrication, the grooves and the components are not sufficiently precise by themselves to reach laser-quality alignment. In other words, the mirrors are not yet perfectly aligned, so at this stage, their glass device is not yet functional as a laser.

The scientists also know from previous research that they can make glass expand or shrink locally. Why not use this technique to adjust the alignment of the mirrors?

The initial etching is therefore designed so that one mirror sits in a groove with micromechanical flexures engineered to locally stir the mirror when exposed to femtosecond laser light. In this way, the commercial femtosecond laser is used a second time, this time to align the mirrors, and ultimately create a stable, small-scale femtosecond laser.

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“This approach to permanently align free-space optical components thanks to laser-matter interaction can be expanded to a broad variety of optical circuits, with extreme alignment resolutions, down to sub-nanometers,” says Bellouard.

Ongoing research programs at the Galatea Lab will explore the use of this technology in the context of quantum optical system assembly, pushing the limit of currently achievable miniaturization and alignment accuracy.

The alignment process is still supervised by a human operator, and with practice can take a few hours to achieve. Despite its small size, the laser is capable of reaching approximately a kiloWatt of peak power and of emitting pulses of less than 200 femtoseconds, barely enough time for light to travel across a human hair.

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This novel femtosecond laser technology is to be spun off by Cassio-P, a company to be headed by Antoine Delgoffe at Galatea Lab, who joined the project at a decisive stage with the mission of finalizing the proof-of-concept into a future commercial device.

“A femtosecond laser replicating itself, are we perhaps reaching the point of self-cloning manufactured devices?” concludes Bellouard.

Reference: “All-glass miniature GHz repetition rate femtosecond laser cavity,” Optica. DOI: doi:10.1364/OPTICA.496503

Matthew Griffin / About Author

Matthew Griffin, described as “The Adviser behind the Advisers” and a “Young Kurzweil,” is the founder and CEO of the World Futures Forum and the 311 Institute, a global Futures and Deep Futures consultancy working across the next 50 years, and is an award winning futurist, and author of “Codex of the Future” series.

Regularly featured in the global media, including AP, BBC, Bloomberg, CNBC, Discovery, RT, Viacom, and WIRED, Matthew’s ability to identify, track, and explain the impacts of hundreds of revolutionary emerging technologies on global culture, industry and society, is unparalleled. Recognised for the past six years as one of the world’s foremost futurists, innovation and strategy experts Matthew is an international speaker who helps governments, investors, multi-nationals and regulators around the world envision, build and lead an inclusive, sustainable future.

A rare talent Matthew’s recent work includes mentoring Lunar XPrize teams, re-envisioning global education and training with the G20, and helping the world’s largest organisations envision and ideate the future of their products and services, industries, and countries.

Matthew's clients include three Prime Ministers and several governments, including the G7, Accenture, Aon, Bain & Co, BCG, Credit Suisse, Dell EMC, Dentons, Deloitte, E&Y, GEMS, Huawei, JPMorgan Chase, KPMG, Lego, McKinsey, PWC, Qualcomm, SAP, Samsung, Sopra Steria, T-Mobile, and many more.