SiGe photonic circuits for mid IR spectroscopy

Mid-infrared (mid-IR) spectroscopy is a nearly universal way to identify chemical and biological substances, as most of the molecules have their vibrational and rotational resonances in the mid-IR wavelength range. The development of silicon-based mid-IR photonic circuits has recently gained a lot of attention. Among the different materials available in silicon photonics, germanium (Ge) and silicon-germanium (SiGe) alloys with a high Ge concentration are particularly interesting because of the wide transparency window of Ge extending up to 15 µm. In this work we will review recent results in the development of photonics circuit based on Ge-rich SiGe waveguides.