Enhanced mid-infrared gas absorption spectroscopic detection using chalcogenide or porous germanium waveguides. (18th February 2021)

• Record Type: Journal Article
• Authors: Zegadi, Rami; Lorrain, Nathalie; Bodiou, Loїc; Guendouz, Mohammed; Ziet, Lahcene; Charrier, Joël
• Is Part Of: Journal of optics. Volume 23:Number 3(2021)
• Publication Date: 2021-02-18
• Subjects: mid-infrared detection -- integrated optical sensors -- power factor -- design -- ridge and slot waveguides -- chalcogenide and porous germanium materials; Optics -- Periodicals; 535.05
• DOI: 10.1088/2040-8986/abdf69
• Languages: English
• ISSNs: 2040-8978

Abstract

Abstract: Different integrated photonic sensors are investigated for the detection in the mid-infrared region of the two gases namely CO2 and CH4 . The three studied structures are ridge waveguides, based both on chalcogenide films (ChG) or porous germanium (PGe) and slot waveguides based on ChG. Waveguide dimensions are optimized to obtain the highest power factor between guided light and gas while maintaining a single mode propagation in the mid-infrared wavelength range. The achievable power factor is 1% in case of ChG ridge-waveguide, 45% for PGe-ridge, and 58% in case of ChG-slot. Extremely low limits of detection (LOD), 0.1 ppm for CO2 at λ = 4.3 μ m and 1.66 ppm for CH4 at λ = 7.7 μ m are obtained for a ChG slot waveguide, due to the large gas absorption coefficients in the mid-infrared spectral range. For PGe waveguides, low LOD values are also computed: 0.12 ppm for CO2 at λ = 4.3 μ m and 1.89 ppm for CH4 at λ = 7.7 μ m. These results show that the proposed structures could achieve competitive performance required for generic spectroscopic detection on a chip for environment and health sensing.