We report high speed integrated electro-optic modulator and integrated photodetector operating in a wide spectral range from 5 to 8 µm wavelength. Modulation is reported up to 1 GHz, while the photodetector responsivity reaches up to 0.1 mA/W. The development of a complete photonic platform including modulator and photodetector paves the way for on chip synchronous detection for multi-molecule on-chip spectroscopic systems.
Spectroscopy in the mid-infrared (mid-IR) wavelength range is a key technique to detect and identify chemical and biological substances. In this context, the development of integrated optics systems paves the way for the realization of compact and cost-effective sensing systems. Among the required devices, an integrated electro-optical modulator (EOM) is a key element for advanced sensing circuits exploiting dual comb spectroscopy. In this paper, we have experimentally demonstrated an integrated EOM operating in a wide wavelength range, i.e. from 5 to 9 µm at radio frequency (RF) as high as 1 GHz. The modulator exploits the variation of free carrier absorption in a Schottky diode embedded in a graded silicon germanium (SiGe) photonic waveguide.
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