A New Era in Laser Technology – Scientists Create Femtosecond Laser Entirely out of Glass

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“Breaking New Ground in Laser Technology: Scientists Develop Glass-Based Femtosecond Laser

In a remarkable feat of innovation, scientists have engineered a compact femtosecond laser entirely from glass, marking a significant breakthrough in laser alignment processes. This advancement holds great promise for the realms of quantum optics and technology miniaturization. The pioneering effort, funded by the European Research Council, is now poised for commercialization. Credit: Jamani Caillet / EPFL

Is it feasible to craft a femtosecond laser solely from glass? This intriguing question led Yves Bellouard, the head of EPFL’s Galatea Laboratory, on a journey after years spent painstakingly aligning femtosecond lasers for laboratory experiments.

The Galatea laboratory stands at the intersection of optics, mechanics, and materials science, with femtosecond lasers playing a pivotal role in Bellouard’s research. These lasers emit extraordinarily brief and consistent bursts of light, finding applications in laser eye surgery, non-linear microscopy, spectroscopy, and sustainable data storage. Conventionally, commercial femtosecond lasers are constructed by mounting optical components on a substrate, necessitating meticulous alignment.

Bellouard and his team devised an ingenious solution: utilizing a commercial femtosecond laser to create a glass-based femtosecond laser, no larger than a credit card and significantly simplifying the alignment process. The findings of this endeavor have been published in the journal Optica.

Crafting a glass-based femtosecond laser

To construct a femtosecond laser using a glass substrate, scientists begin with a glass sheet. Bellouard explains the choice of glass, emphasizing its lower thermal expansion compared to traditional substrates, stability, and transparency to the laser light used.

Utilizing a commercial femtosecond laser, researchers etch precise grooves into the glass, facilitating the precise placement of crucial laser components. However, even at micron-level precision, the grooves and components alone do not achieve laser-quality alignment. In other words, the mirrors are not perfectly aligned at this stage, rendering the glass device non-functional as a laser.

Drawing from previous research, scientists leverage the ability to locally expand or shrink the glass. They use this technique to fine-tune the mirror alignment.

The initial etching is designed to position one mirror within a groove with micromechanical flexures, which can be manipulated locally when exposed to femtosecond laser light. This secondary use of the commercial femtosecond laser aligns the mirrors, ultimately creating a stable, miniaturized femtosecond laser.

Bellouard notes, “This approach to aligning free-space optical components through laser-matter interaction can be extended to a wide range of optical circuits, achieving extreme alignment precision, down to sub-nanometer levels.”

Applications and Beyond

Ongoing research initiatives at the Galatea Lab will explore the integration of this technology in the context of quantum optical system assembly, pushing the boundaries of miniaturization and alignment accuracy.

Although a human operator still oversees the alignment process, with practice, it can be accomplished in a matter of hours. Despite its diminutive size, this laser can produce roughly a kilowatt of peak power and emit pulses lasting less than 200 femtoseconds—barely enough time for light to traverse a human hair.

This groundbreaking femtosecond laser technology will be spun off by Cassio-P, a company led by Antoine Delgoffe at Galatea Lab. Delgoffe joined the project at a critical stage with the goal of transforming the proof-of-concept into a future commercial device.

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

Reference: “All-glass miniature GHz repetition rate femtosecond laser cavity” by Antoine Delgoffe, Clemens Hönninger, Sargis Hakobyan, Yves Bellouard and Saood Nazir, 19 October 2023, Optica. DOI: doi:10.1364/OPTICA.496503

This research received funding from the European Research Council under an ERC PoC grant for the GigamFemto project, aimed at demonstrating a gigahertz femtosecond laser on a single glass chip. The spin-off activities were supported through the Bridge Proof-of-Concept and EPFL’s Ignition programs.”

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More about Laser Technology Advancement

• Optica Journal Article – The original research article titled “All-glass miniature GHz repetition rate femtosecond laser cavity” by Antoine Delgoffe, Clemens Hönninger, Sargis Hakobyan, Yves Bellouard, and Saood Nazir, published in Optica.

• European Research Council (ERC) – Information about the European Research Council, which provided funding for the GigamFemto project.

• Cassio-P – The company responsible for commercializing the glass-based femtosecond laser technology, led by Antoine Delgoffe at Galatea Lab.

• EPFL’s Ignition Programs – Details about EPFL’s Ignition programs, which supported the spin-off activities related to this technology.