Periodic Reporting for period 1 - EXTREMELIGHT (EXTREME ENVIRONMENT RESISTANT NANOPHOTONICS) Période du rapport: 2017-05-02 au 2019-05-01 Résumé du contexte et des objectifs généraux du projet Nanophotonic extreme environment sensors are expected to lead to revolutionary advancements in aerospace, nuclear, wellbore exploration and environmental bio-chemical sciences. Extreme environments are those where the physico-chemical conditions render standard materials completely unusable; including strongly ionizing radiation, high erosion, high corrosion, or temperatures beyond 1600°C in aircraft and aerospace applications.Recently, yttrium aluminum garnet (YAG) crystals have been identified as a harsh environment resistant optical material thanks to its unique combination of outstanding optical properties and high melting temperature (1970°C), high chemical inertness and hardness. However, micro or nanostructuring of YAG components is typically impossible due to its ability to withstand plasma corrosion in etching chambers and also fast fracture under high stress machining or milling processes.The central question that this project aims to solve is if it is possible to fabricate three-dimensional air-dielectric nanostructures inside YAG crystals so as to design functional nanophotonic circuits inside single crystals for future extreme-environment high-performance sensors.The EXTREMELIGHT project combines a unique YAG-nanostructuring breakthrough technology developed by the experienced researcher Dr. Ródenas, with the recognized expertise of the academic Host (the FAST group, directed by Dr. Osellame at the IFN-CNR) in lab-on-chip photonics, and of the Industrial Partner in high-performance integrated spectrometers, for exploring the development of a first proof-of-concept YAG nanophotonics technology which could lead to a novel generation of high-performance integrated nanophotonics capable of withstanding the most extreme environments. Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent The novel three-dimentional nanostructuring nonlinear laser lithography technique has been developed, as to a level to achieve feature sizes on the 100-nm level.The technique has been developed so as to be applied not only to YAG laser crystals, but also to sapphire crystals, both optical crystals widely spread across world-wide industries, not only for optics and lasers industries in general, but also for other areas involving mobile smart phones and smart watchs, among many others.Proof-of-concept nanophotonic devices have been developed, such as high-efficiency sub-wavelength gratings and photonic waveguides.Across the timeline of EXTREMELIGHT, several high-impact international conferences have been attended for scientific dissemination of the different results obtained, and at least twice a year: An Invited talk was given at the international Laser Precision Microfabrication LPM 2017, an oral talk was given at CLEO/Europe-EQEC 2017, also at SPIE Photonic West 2018 and also at Laser Precision Microfabrication LPM 2018. An Invited talk was also given at the International Conference on Advanced Laser Technologies ALT18. Finally, another oral talk was given at CLEO/Europe-EQEC 2019.Results achieved up to 2019 have been published in the journal Nature Photonics (https://doi.org/10.1038/s41566-018-0327-9). Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent) The present work goes beyond the state of the art in lithography techniques for fabricating nanophotonic devices, allowing for the first time, to produce 3D nanophotonic circuits inside optical crystals, which up to now where only feasible in twodimension only at the crystal surface, but not inside its volume and in 3D. This Copernican twist may now allow to fabricate photonic devices inside optical crystals which where previously undreamt-of. The 3D nanolithography technique could allow to transfer concepts for nanophotonics and ultrafast laser optics fields to the fields of solid state rare-earth doped laser crystals and classical optics. The impact could be very high since it could represent a new fabrication platform to exploit long awaited for concepts such as those of photonic crystal nanolasers, sensors, optical fibers and lasers in general, which so far have been impossible to fabricate due to the impossibility of fabricating large-scale, high quality, three-dimensional, optical nano-materials. Furthermore, due to the particular physical and chemical properties of these crystals to resist extreme environments, the new nanophotonic engineered crystals could be used to develop a new platform for photonic devices capable of operating in extreme environments, where standard silicon nanophotonics and plasmonics are of no use. Picture of a sub-wavelength grating laser-fabricated inside a YAG crystal.
