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Mid-infrared integrated photonics with Ge quantum wells.

Frigerio J., Barzaghi A., Falcone V., Calcaterra S., Giani R., Ballabio A., Isella G., Chrastina D., Ortolani M., Virgilio M.
  Lunedì 12/09   14:00 - 19:00   Aula D - Marianna Ciccone   II - Fisica della materia   Presentazione
In recent years, mid-infrared (MIR) integrated photonics has raised an increasing interest due to the envisioned applications in molecular sensing, environmental monitoring and security. Nowadays, MIR photonics based on the silicon-on-insulator platform, working up to $3.2 \mu m$ has already reached a high technology readiness level. Nevertheless, extending the operational wavelength toward the long-wave-infrared (LWIR) is still challenging and key functionalities such as photodetection, high-speed modulation and wavelength conversion are still not available. In this framework, Ge/SiGe quantum wells could be exploited to fill the gap. Intersubband optical transitions in the valence band of such heterostructures can be used for light detection, for high-speed modulation through the quantum confined Stark effect (QCSE), and for wavelength conversion through second-harmonic generation. Ge/SiGe QWs can be easily grown on top of SiGe buffers, making them fully compatible with the existing SiGe-on-Si material platform. In this contribution, we show an experimental demonstration of second-harmonic generation and a preliminary study for the realization of integrated modulators and photodetectors.