Effects of scattering by inhomogeneous media on the performance of integrated grating couplers

During the last decades, great interest has arisen towards the developing of integrated optical devices based on the use of biocompatible materials, which can be used to implement sub-skin implantable and bioresorbable optical sensors. Silk fibroins for example, have shown excellent properties such as transparency in the visible wavelength range and ease of biological functionalization [1], and could be used for the fabrication of optical devices with sub-micrometric dimensions employing an indirect patterning approach. A possible way to in/out couple these optical devices is represented by diffractive grating couplers (GCs): while this approach has already proven to be highly efficient in the Silicon-on-Insulator (SOI) platform [2], its application to sub-skin optical devices is limited by the detrimental effects of light propagation inside the skin, represented by scattering and attenuation.