Electro-optic frequency comb generation in the mid-infrared.

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Mid-infrared (mid-IR) spectroscopy is a nearly universal way to identify chemical and biological substances and to perform non-invasive diagnostics. More specifically, the 6-15 µm wavelength range can be exploited to detect small traces of environmentally hazardous and toxic substances for a variety of applications including defense, security and industrial monitoring. While current optical systems in the mid-IR range are based on bulky assemblies of discrete devices, a challenging task is to make mid-IR spectroscopy accessible in remote areas, driving the development of compact and cost-effective solutions to replace table-top systems. In the project we aim at addressing new routes for high resolution spectroscopic systems based on dual-comb spectroscopy by developing innovative frequency comb sources. The strategy developed in ELECTROPHOT is based on the unique properties of graded index Silicon Germanium (SiGe) photonics circuits, which are their transparency in a wide spectral range together with the ability to fine tune both the electronic bandgap and refractive index of SiGe alloys, to make large progress in mid-IR photonics. Based on these capabilities, the original idea of the project is to exploit simultaneously optical nonlinear and electro-optic comb generation, to generate compact frequency comb sources providing simultaneously wideband operation with fine and tunable resolution. Interestingly the photonics circuits will leverage from reliable and high-volume fabrication technologies, already developed for microelectronic integrated circuits to provides a new playground in mid-IR photonics.