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The affordable and easily accessible sensing of greenhouse gases is a vital Smart City application, serving both climate targets, and digitization goals at a European level. Commonly used spectroscopic solutions, although reliable, remain bulky and costly. Integrated photonics can fill the need for ubiquitous air testing, offering robust, miniaturized systems, with low cost. We present a study of a MID-IR spectroscopy sensing system developed on a silicon photonics platform, utilizing a Bragg grating mirror cavity. For each targeted gas, an optical cavity is designed, allowing the use of multimode radiation in its dedicated spectral window, therefore increasing the interaction length in the silicon waveguide., Part of ISBN 9781510673168QC 20240827

Low-cost, easily integrable photodetectors (PDs) for silicon (Si) photonics are still a bottleneck for photonic-integrated circuits (PICs), especially for wavelengths above 1.8 mu m. Multilayered platinum diselenide (PtSe2) is a semi-metallic two-dimensional (2D) material that can be synthesized below 450 degrees C. We integrate PtSe2-based PDs directly by conformal growth on Si waveguides. The PDs operate at 1550 nm wavelength with a maximum responsivity of 11 mA/W and response times below 8.4 mu s. Fourier-transform IR spectroscopy in the wavelength range from 1.25 to 28 mu m indicates the suitability of PtSe2 for PDs far into the IR wavelength range. Our PtSe2 PDs integrated by direct growth outperform PtSe2 PDs manufactured by standard 2D layer transfer. The combination of IR responsivity, chemical stability, selective and conformal growth at low temperatures, and the potential for high carrier mobility makes PtSe2 an attractive 2D material for optoelectronics and PICs., QC 20220426

We show detection of CO2 concentrations as low as 500 ppm using a suspended silicon photonic mid-IR waveguide. The performance is enabled by the low propagation loss (2.35 ±0.25) dB/cm permitting sensing with waveguides up to 7 cm in length., Part of ISBN 9781557528209QC 20230622