Mid-infrared integrated photonics with Ge-rich SiGe waveguides

Overview & Synopsis

The recent interest towards applications of spectroscopy for chemical and biological sensing in the mid-infrared (mid-IR) has prompted the need for a new class of photonic integrated circuits operating in this important spectral region. In this context, germanium is considered a key material thanks to its transparency in the 2-15 μm range [1] and its compatibility with standard silicon foundry processes. Ge-rich SiGe layers on top of graded buffers were already successfully employed as waveguides at telecom wavelengths [2] and they were recently proposed as promising platform to develop optical components operating in the mid-IR, offering high versatility and broadband transparency by choosing a suitable Ge content in the alloy and by tailoring the vertical graded refractive index profile to optimize mode confinement. In this work we present our recent results on the realization and characterization of low-loss waveguides and ul-tra-wideband Mach-Zehnder modulator operating in the mid-infrared. The perspectives about the realization of non-linear devices based on this material platform will also be discussed.