Nanoparticle doped materials

The incorporation of laser active nanoparticles in amorphous host materials such as fused silica offers additional design space for the development of novel gain materials. We study the fluorescence and laser properties of rare-earth doped nanocrystals which differ substantially from their bulk counterparts. This is due to the dominating influence of active ions on the surface of the nanocrystals. In contrast to macroscopic bulk crystals where all active ions are located within the volume of the crystal, the energy transfers to neighbouring ions and also to the amorphous host is significantly altered. We developed a numerical tool to study all energy transfer mechanisms in nanocrystals which allows us to optimise nanocrystals in terms of structure, size and doping concentration. The numerical simulations are supported by extensive measurements of optical properties of nanocrystals such as radiative lifetime and quantum efficiency measurements enabling quantitative predictions on the optical performance of different nanocrystals. This will enable new designs of laser-active fibres, e.g. for visible lasers, previously prevented by the strong multi-phonon quenching to the fused silica host. We furthermore study the applicability of nanocrystals for other optical applications such as high-resolution temperature measurements beyond the diffraction limit of conventional optical techniques.