Low-Loss Mid-Infrared SOI Slot Waveguides

Mid-infrared sensing is a field that has recently attracted attention due to the potential to reach the fingerprint region for several chemical compounds, allowing enhanced sensitivity. To further enhance the sensitivity of photonic sensors slot waveguides can be used as waveguides as the electric field amplitude can be greatly increased in the gap region. In this letter, we present silicon on insulator slot waveguides with a 1.4 ± 0.2 dB/cm propagation loss at 3.8 μm wavelength, as well as strip to slot transitions with a loss of 0.09 ± 0.01 dB/transition and slot bends with a loss of 0.18 dB/bend.