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Plenary lectures
The birth of fluoride glass The beauty in science is that, when expecting a result, you find something very different which open the way to fruitful discoveries. That is happen with the birth of Fluoride Glasses. In changing a little bit the composition of some Rare Earths fluoro-zirconates we found accidentally, in opening the sealed tube, beautiful large “crystals”. They were too large to be honest. Indeed, after a brief X Ray investigation those materials was pieces of glass. Vitreous compounds was not in our culture of solid state chemist but the beauty of this fluorides materials change our mind and we decided to enter in this new field. After publishing the first results, we received a lot of publicity from two institution. First the Lawrence Livermore National Laboratory in charge of the Laser Fusion program. They selected the FG because of their weak non-linear property and their high contents of Neodymium. The second is the family of telecom research laboratories because of the potential ultra-transparency of FG due to their large optical window.
From solid state chemistry to glass science and optical fibers The serendipitous discovery of fluoride glasses originates from systematic synthesis based on crystal chemistry concepts. Physico-chemical properties and potential applications were investigated. Later, emphasis was put on ultra-low loss optical fibers, leading to intense research activity in many laboratories and most telecom companies. A brief review of important researchers and groups will be presented.
Novel fiber photonics based on fluoride fiber When fluoride glass was discovered, it attracted a lot of attention as a new optical fiber medium which had a potential to outperform the transmission loss of silica fiber. New fiber technologies which were not based on the conventional silica fiber technologies were generated through the fluoride optical fiber research. It realized performance especially in the field of optical amplifiers and lasers, and fiber nonlinear optics not achievable with silica fiber and it opened a new prospect of fiber optics research and photonics. Here I present our research activities looking back at a history of fluoride fiber research.
Fluoride Fiber Technology: The chalenges to Bring Exotic Technologies to the Market The presentation will first review the development of fluoride glass and fiber technology from 1974 to the present. It will also highlight Dr. Saad’s contribution to this technology, including the role played by IRphotonics and Thorlabs team. Dr. Saad founded IRphotonics in 2003 to renew the interest into fluoride fiber technology by the end users, which he successfully accomplished with commercial and military customers. The presentation will then focus on different challenges one can face while trying to commercialize exotic technologies.
Recent advances in fluoride fiber lasers Laser technologies are now an integral part of the vast majority of cutting-edge developments. Fiber lasers have carved out a place of choice in this ecosystem, thanks to their robustness, reliability and propensity to power scaling. In recent years, the development of low-loss fluoride glass fibers, heavily doped with lanthanide ions, has made it possible to considerably extend the operating range of fiber lasers, from the visible to the mid-infrared, a range that was previously limited to the near infrared due to the intrinsic properties of silica fibers. The availability of powerful fiber lasers at these non-traditional wavelengths is now enabling new high-end applications in a variety of innovative fields, including medicine, environmental science, materials processing and defense & security. During this presentation, a review of recent advances in the development of powerful fluoride fiber lasers operating from the visible to the mid-infrared will be detailed.
From stars to black holes, 30 years of interferometry with fluoride glass fibers Interferometers are synthetic telescopes in which the light collected by different apertures is coherently interfered. The technique, devised by Fizeau and Michelson, allows to increase the resolving power of a single telescope to that of a fictional telescope whose diameter would be as large as the maximum distance of apertures in the array. The resolving power can be increased by factors of ten or hundred and even more in theory. In practice, this is not so straightforward and several difficulties need to be overcome. One of the them is the destruction of spatial coherence by the turbulence of the atmosphere. One technique has proved very efficient to solve this problem: light from individual apertures is injected into single-mode fibers. This was demonstrated in the 90s with the FLUOR instrument built in collaboration with Le Verre Fluoré and using their single-mode fibers. First unprecedented results were obtained on stars. The technique was expanded to link telescopes with LVF fibers atop the Maunakea in Hawai’i which has been instrumental to lake build the GRAVITY instrument at ESO’s Very Large Telescope in Chile. Extraordinary results have been obtained on the supermassive black hole at the center of our galaxy. And on other supermassive black holes at the center of other more distant galaxies. I will walk through this journey during my talk and show some of the results. |
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