Runtime: 01.01.2019 - 31.12.2022
This project will set a new horizon in the world of fibre lasers by demonstrating a ground-breaking new idea for the fabrication of fibres containing active nanocrystals (NCs). Today’s successful fibre lasers are fabricated from robust and durable rare-earth-activated silica glasses. However, the high phonon energies in silica exclude most lasers in the visible (lam<900nm) and mid-infrared (lam>2000nm) spectrum and also multiphonon-quenched transitions in the usual (lam=900-2000 nm) spectrum. Besides, the lack of a well-defined local host structure excludes most transition-metal lasers. The operation of oxide glass fibre lasers can be extended to an enormous spectral range (~400–4500 nm) and many transitions already demonstrated in bulk crystalline materials, by doping oxide glasses with active NCs optimized for the particular laser wavelength. Previously, neither the growth of NCs by a fibre heat treatment nor their incorporation during glass formation has shown convincing results. The latter is hampered by the size-related melting point depression of the NCs below the critical glass temperature of the host. Our project will solve this problem by grinding the glass host material to
even smaller nanoparticles, thereby lowering the critical glass temperature below the NCs melting point, and subsequently applying a specialized powder-sintering method for the fabrication of fibres. In this way, NCs are pre-processed independently of the glass host, ideally the fibre fabrication is reduced to a single thermal process which is survived by the NCs. Post-processing of the drawn fibre is avoided. In this project, we will fabricate sapphire and sesquioxide NCs, incorporate them into BaO-Ga2O3-GeO2 glass, fabricate thin films and preforms, draw fibres, and demonstrate two crucial
laser transitions: i) a Ti3+:Sapphire-NC fibre laser tuneable around 800 nm; ii) a Pr3+:Sesquioxide-NC 1300-nm fibre laser enabling a much-awaited wavelength extension in tele-communication.
The project is funded by EU-H2020 under the number GA 829161.