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Proceedings Paper

Suspended silicon waveguide for mid-infrared gas sensing
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Paper Abstract

An integrated refractive index gas sensor working in the Mid infrared (MIR) region and utilizing suspended silicon waveguide is presented. Although many integrated refractive index gas sensors have been proposed in the literatures, their operating wavelength is limited to the near infrared range. Our proposed gas sensors can operate in the mid infrared up to 10μm, were many gases have their absorption fingerprints in order to enhance the sensing performance. A finite difference solver is used to perform the sensitivity analysis of the suspended silicon waveguide in the MIR range for gaseous medium. The analysis shows that a suspended silicon waveguide can achieve high waveguide sensitivity with a minimal mode loss. Thus, we designed a high performance Mach Zehnder Interferometer (MZI) gas sensor using a suspended silicon waveguide as the sensing arm. Three dimensional finite difference time domain (3D-FDTD) solver is used in the design and optimization of two designs. One for the wavelength interrogation scheme of detection and another one for the intensity interrogation scheme. The first design, exhibits high wavelength sensitivity S=7028 nm/RIU and can reach high figure of merit (FOM) of around 180 RIU-1 for both wavelength and intensity interrogation methods with only 250μm sensing arm length. The second design furtherly enhances the intensity interrogation FOM to reach 370RIU-1 at the same length. Intensity interrogation needs only a laser source and a detector. Hence, using our sensor in intensity interrogation based read-out offers compact, low cost and mass scale fabrication which makes our proposed sensor a good platform for lab on chip technology.

Paper Details

Date Published: 25 February 2020
PDF: 8 pages
Proc. SPIE 11283, Integrated Optics: Devices, Materials, and Technologies XXIV, 112830M (25 February 2020); doi: 10.1117/12.2545897
Show Author Affiliations
Raghi S. El Shamy, The American Univ. in Cairo (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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