Chiral plasmonic metasurface assembled by DNA origami.

Chiral materials are essential to perceive photonic devices that control the helicity of light. However, the chirality of natural materials is rather weak, and relatively thick films are needed for noticeable effects. To overcome this limitation, artificial photonic materials were suggested to affect the chiral response in a much more substantial manner. Ideally, a single layer of such a material, a metasurface, should already be sufficient. While various structures fabricated with top-down nanofabrication technologies have already been reported, here we propose to utilize scaffolded DNA origami technology, a scalable bottom-up approach for metamolecule production, to fabricate a chiral metasurface. We introduce a chiral plasmonic metamolecule in the shape of a tripod and simulate its optical properties. By fixing the metamolecule to a rectangular planar origami, the tripods can be assembled into a 2D DNA origami crystal that forms a chiral metasurface. We simulate the optical properties but also fabricate selected devices to assess the experimental feasibility of the suggested approach critically.

Self-stabilizing curved metasurfaces as a sail for light-propelled spacecrafts.

Laser-driven spacecrafts are promising candidates for explorations to outer space. These spacecrafts should accelerate to a fraction of the speed of light upon illumination with earth-based laser systems. There are several challenges for such an ambitious mission that needs to be addressed yet. A matter of utmost importance is the stability of the spacecraft during the acceleration. Furthermore, the spacecraft sails should effectively reflect the light without absorptive-overheating. To address these requirements, we propose the design of a lightweight, low-absorbing, high-reflective, and self-stabilizing curved metasurface made from c-Si nanoparticles. A method to determine the stability is presented and, based on the multipole expansion method, the rotational stability of the curved metasurfaces is examined and the optimal operating regime is identified. The curvature is shown to be beneficial for the overall stability of the metasurface. The validity of the method is verified through numerical simulations of the time evolution of the trajectory of an identified metasurface. The results show that curved metasurfaces are a promising candidate for laser-driven spacecrafts.