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Multiphoton photopolymerisation (MPP), also known as 3D nanoprinting, was studied using a wavelength-tunable femtosecond laser. The possibility of using any colour of the spectrum from 500 to 1200 nm with a fixed pulse width of 100 fs revealed an interplay of photophysical mechanisms more delicate than just two-photon photopolymerisation. An effective order of absorption, i.e. the X-photon absorption, as well as optimal exposure conditions were assessed for photosensitised and pure SZ2080TM pre-polymer. The tunability of wavelength greatly influenced the dynamic fabrication window (DFW), optimised conditions resulting in a 10-fold increase. Furthermore, a non-trivial energy deposition by X-photon absorption was noted with an onset of a strong lateral size increase at longer wavelengths and can be understood as due to reaching epsilon-near-zero conditions. Such a control over the voxel aspect ratio and, consequently, the photopolymerised volume, may boost 3D nanoprinting efficiency. Overall, the results reveal wavelength being an important degree of freedom to tailor the MPP process and, if optimised, benefiting broad applications in areas of micro-optics, nanophotonic devices, metamaterials and tissue engineering. [ABSTRACT FROM AUTHOR]

The fabrication of polymer–metal hybrids in an additive process makes it possible to further improve the geometrical and material adaption in a multi-material design. In this work, PLA is fabricated through a fused filament fabrication process on AlSi10Mg structures manufactured by laser powder bed fusion. The mechanical connection is realised by form fit, for which different geometries are examined through tensile tests. Deep penetration of the PLA into the metallic structures is achieved by optimisation of the process parameters. The penetration depth is assessed through the use of micro-computed tomography. Finally, the interplay of mechanisms leading to a firm connection is discussed. [ABSTRACT FROM AUTHOR]

This paper reports an experimental study of the shot-to-shot intensity and spectral distribution fluctuations in the femtosecond coherent pulses from the storage ring (SR) based seeded free electron laser (FEL) at DELTA. A unique implementation of a gated ICCD camera coupled to a Czerny-Turner monochromator is utilized to reveal the details of the individual spectra and intensity of femtosecond pulses accompanied by a significant synchrotron background. This technique demonstrates the potential to study the dynamics of the electron bunches in an SR by scanning over a single electron bunch with seeded femtosecond laser pulses at a subharmonic repetition rate. To the best of our knowledge, this picture provides the first direct experimental evaluation of shot-to-shot intensity and spectral fluctuation in seeded SR-based FELs. [ABSTRACT FROM AUTHOR]