Periodic Reporting for period 1 - HELICOID (Bio-inspired helicoidal multilayers for photonic innovation)
Reporting period: 2017-11-15 to 2019-11-14
This project aimed at exploring a novel thin film fabrication technique to enable the fabrication of artificial multilayers with such infrastructures embedded within the layers, which could lead to novel optical devices. Specifically, inspired by the helicoidal structure found in scarab beetles, a roll-up thin film self-assembly technique was explored to generate multilayer stacks from pre-patterned thin films on a single step. Such an approach would require significantly less fabrication steps than the state-of-the-art multilevel alignment approaches.
The main objectives of this action were 1) to take advantage of optical simulations to study and design multilayers with embedded nanopatterns and 2) to combine state-of-the-art nano-patterning techniques with a roll-up thin film technology to develop a multi-layer platform with engineered patterns at each layer of the stack.
During the project, for the proof-of-concept of this fabrication approach, the work focused on realizing self-rolled multilayers with embedded gold nanoparticles, which due to their strong plasmonic response, could enable us to achieve the selective circular polarization responses with few layer systems. The fabrication of such structures was successful and proved that such technique can be use to enable self-rolled multilayered metasurfaces in general, the main results have been published in a peer reviewed journal. Furthermore, we also explored the fabrication of other types of multilayered metamaterials such as hyperbolic multilayers. The results of the latter are in the process of preparation for a publication.
The development of these type of new fabrication approaches can benefit the scientific community to enable new avenues to create novel materials and components. In this context, the results from this work could lead to innovative photonic technologies with potential applications in security labels, optoelectronic devices, sensing or imaging systems.
The second stage of the project dealt with developing the fabrication protocols to enable the thin film self-rolling of dielectric layers with gold nanoparticle arrays on top. This stage took place at cleanroom nano/micro-fabrication facilities. Different techniques including thin film deposition, photolithography, etching and electron-beam lithography were implemented.
Along side the sample fabrication period, structural characterization was performed using scanning electron microscopy, while the structures were characterized optically via reflection spectroscopy using circularly polarized light. We could demonstrate structures with selective response of circularly polarized light.
Details on the developed fabrication protocols can be found in the open access publication, alongside the optical characterization for helicoidally stacked gold nanoparticle arrays. (https://pubs.acs.org/doi/10.1021/acsphotonics.9b00816). Besides the open access publication, the results were disseminated in several international conferences such as Living Light 2018 in Cambridge, United Kingdom (2nd place poster prize), International Workshop on Nanomembrane Origami Technology, Shanghai, China (invited talk), Gordon Conference in Plasmonics 2018 in Maine, United States, and the Surface Plasmon Photonics 9 in Copenhagen Denmark (best poster prize).