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Proceedings Paper

Waveguides sensitivity analysis for mid-infrared gas sensing
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Paper Abstract

In this work we study various types of photonic waveguides for gas sensing in mid-infrared (MIR) region. MIR region which contains the absorption peaks of many gases is the most suitable region for gas detection. Operating near the absorption peak of the gas to be detected enhance the sensor performance significantly as both real and imaginary parts of the detected gas refractive index are maximized, which enhance the sensitivity and leads to lower detection limit. Here we focus on refractive index sensors that relies on the detection of the real part (n) of the refractive index. Refractive index sensors are strong candidates for integrated on chip sensors, where a small sample volume is needed. One of the main parameters in designing refractive index sensor is waveguide sensitivity which is defined as the ratio of the waveguide effective index change to the medium refractive index change, Swg=Δneff/Δnmed. Thus rigorous sensitivity analysis using full-vectorial finite difference mode solver have been carried out to determine the waveguide sensitivity of such waveguides to gaseous medium. We use silicon on sapphire (SOS) platform to operate in the MIR region from 2μm to 6μm. For each structure we make sensitivity analysis once with undoped silicon and once with doped silicon to show how converting the same structure from dielectric to plasmonic will affect its performance as sensor. The dependence of the effective index, sensitivity and mode loss of each waveguide on the different waveguide dimensions was studied. Finally, a comparison between the proposed waveguides is provided.

Paper Details

Date Published: 25 February 2020
PDF: 9 pages
Proc. SPIE 11283, Integrated Optics: Devices, Materials, and Technologies XXIV, 1128322 (25 February 2020); doi: 10.1117/12.2545068
Show Author Affiliations
Raghi S. El Shamy, The American Univ. in Cairo (Egypt)
Ain Shams Univ. (Egypt)
Mohamed A. Swillam, The American Univ. in Cairo (Egypt)
Diaa A. Khalil, Ain Shams Univ. (Egypt)


Published in SPIE Proceedings Vol. 11283:
Integrated Optics: Devices, Materials, and Technologies XXIV
Sonia M. García-Blanco; Pavel Cheben, Editor(s)

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