Invited Speaker Abstract: Nanostructures can be used to tailor light-matter interaction in many ways: Plasmonic nanoantennas composed of metallic nanoparticles enable the control and manipulation of optical energy in the visible and near-infrared spectrum. Periodic arrangements of subwavelength-scaled dielectric nanostructures can act as wavelength- or polarization-selective filters. Combining these nanostructures with optoelectronic devices enables the manipulation of wavelength-dependent device properties. We present and discuss examples how this can be leveraged to fine-tune Germanium heterostructure photodetectors for applications with a particular focus on refractive index sensing.