Physics colloquium

CMOS-compatible Metasurfaces Integrated with Optoelectronic Devices: Tuning Light-matter Interaction at the Nanoscale

Prof. Dr. habil. Inga Fischer

Brandenburg Technical University Cottbus-Senftenberg, Experimental Physics and Functional Materials

Abstract:

Nanostructures can be used to tailor light-matter interaction in many ways. In recent years, optical metasurfaces consisting of two-dimensional arrangements of sub-wavelength sized metallic or dielectric nanostructures have attracted increasing interest, with applications ranging from ultra-thin lenses or filters to sensing. Optical metasurfaces can be realized by structuring thin metallic or dielectric films – as such, they are not only able to profit from nanostructuring methods developed for semiconductor device fabrication but also have the potential to be integrated into device fabrication processes, with the aim of harnessing their properties for optoelectronic devices. While research on optical metasurfaces in general is a strong and growing field, the integration of metasurfaces into optoelectronic devices has been given much less attention. Indeed, there are challenges e.g. related to the requirement that contacting layers have to be present. Furthermore, structural imperfections can strongly influence optical properties of the metasurfaces and are typically more prevalent in more complicated fabrication processes. We currently focus on two possible application areas for optical metasurfaces integrated into optoelectronic devices. In this talk, I will discuss device approaches to refractive index sensing using metallic nanohole arrays on Ge photodetectors. Secondly, I will present recent results related to the incorporation of metasurfaces as wavelength-selective filters into Ge photodetectors for on-chip spectroscopy.