11- Tailoring diffusive transport of light

A large part of linear optics & photonics aims at achieving specific functions of optical systems and devices by molding the flow of light. In ballistic optics, this task is routinely accomplished by tailoring spatial distributions of the refractive index (tensor). In the case of disordered light-scattering media, the situation used to be less clear. Broadly speaking, the aim of this project is to solve this task by designing and realizing spatial distributions of the light diffusivity (tensor). More specifically, we focus on invisibility cloaking structures. Possible applications include high-end security features and the homogenization of the light emission from large-area OLEDs by making top metal contacts invisible. The latter aspect is in collaboration with Uli Lemmer’s group in this DFG-SPP.

Our plans for the second three-year funding period comprise three objectives, a)-c). The first two objectives aim at fundamental science aspects, the third objective aims at getting closer to real-world applications. We will perform the work on objective 3) in collaboration with the groups of Uli Lemmer and Guillaume Gomard within this DFG-SPP 1839 program, just as the preliminary work described above.

a) Realize experimentally a multi-layer laminated invisibility cloak in the diffusive regime of light propagation that also works under transient illumination conditions. This objective follows a previous theoretical prediction by a Spanish group.

b) Investigate the role of open and closed eigenchannels in invisibility cloaking structures experimentally. A pre-requisite for this objective is the realization of more long-term stable structures.

c) Work towards 3D laser micro-printed tailored disordered structures for molding the flow of diffuse light. 3D printing brings the ideas of this project closer to real-world applications. As a model example, we will realize cloaked contacts on OLEDs.