Low loss dielectric loaded plasmonic waveguides for sensing applications above nine microns

Dielectric-Loaded Surface Plasmon Polariton Waveguides (DLSPPWs) offer a simple and effective solution for compact on-chip transmission and guiding of light for different optoelectronic applications. Especially, they offer a platform for chemical analysis enabled by efficient on-chip laser-detector coupling [1] when the optical mode guided along the sample surface is propagating (>95%) in the surrounding medium e.g. air. For longwave infrared (LWIR) applications (8-12 µm) however, the material selection is challenging as most common dielectrics like PMMA, Silica or Silicon Nitride absorb in this wavelength range [2] , [3] . As undoped Ge has low optical losses up to 14 µm, we investigated its performances as dielectric material for LWIR plasmonics.