Laser-induced forward transfer of pre-machined donor films
Micro-pellets of ZnO with a diameter of 5-10 μm and extremely smooth edges have been printed using laser-induced forward transfer from 1 μm thick films, that had been prepatterned using focussed ion beam (FIB) machining.
Laser-induced forward transfer techniques for printing functional materials and photonic devices
The subject of this thesis is to study the Laser-Induced Forward Transfer (LIFT) technique using a time-resolved method in order to gain a better insight into the dynamics of the transfer process and to use the technique for rapid prototyping of photonic devices and printing piezoelectric materials for energy harvesting applications. A nanosecond shadowgraphy technique was used to study the triazene polymer (TP)-dynamic release layer (DRL) assisted LIFT technique for solid-phase ceramic materials namely gadolinium gallium oxide (Gd-Ga-O) and ytterbium doped yttrium aluminium oxide (Yb:YAG). The dependence of the distance travelled by the shockwave and the ejected donor material, their velocities and the quality of the ejected donor pixel on the laser fluence, the thickness of the TP-DRL and donor film thickness was studied and is discussed. Segmented channel waveguides, X-couplers and mode-filters based on titanium (Ti) indiffused lithium niobate (LN) have been fabricated using the LIFT technique. The segment separation was found to be the key factor in determining mode profiles of waveguides. The corrugations due to the segmented nature of the deposits was observed to introduce non-adiabatic behavior in the mode filters which was further confirmed by theoretical modeling. Forward transfer of donor films with patterns to be transferred machined into them prior to LIFT have been investigated. This technique allows debris-free printing of thicker and fragile donors films with extremely smooth and uniform edges in intact and solid-phase without the need of any sacrificial layer. Results of debris-free printing of micro-pellets of zinc oxide (ZnO) with extremely good quality edges from donor films pre-machined using focused ion beam (FIB) are presented. Printing and post-transfer characterization of both lead zirconate titanate (PZT) and non-lead based ZnO piezoelectric materials for energy harvesting applications using the LIFT and TP-DRL assisted LIFT techniques have been studied and discussed.
Dynamics of long-pulse laser transfer of micrometer-sized metal patterns as followed by time-resolved measurements of reflectivity and transmittance
Laser‐induced transfer of thin films is a simple single‐step technique for surface patterning. In this paper the optimization principles and processes are outlined which led to successful application of the long‐pulse laser transfer technique. The critical analysis of experiments on ns‐pulse laser transfer of thin films of a variety of metals and the optimization study of the long‐pulse laser transfer technique suggests that efficient deposition of high‐quality patterns of micrometer dimensions can only be expected when using long laser pulses which not only produce ablation of the thin film pattern in solid phase but also maintain sufficient temperature during transfer and even on landing, to ensure film adherence. In order to identify and understand the different time‐dependent processes determining the laser transfer, studies using optical and electron microscopy and static and time‐resolved optical measurements were performed.