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12 April 2019 A compact silicon-on-insulator gas sensor
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Proceedings Volume 10923, Silicon Photonics XIV; 109231M (2019)
Event: SPIE OPTO, 2019, San Francisco, California, United States
Gas sensors have been widely used for different applications including chemical detection, quality assurance, environmental monitoring and medical diagnostics. Optical gas sensors exhibit higher sensitivity and wider dynamic range than their electrical counterparts. This work demonstrates a novel design for a gas sensor based on conventional Silicon-on-insulator (SOI) platform. The sensor design is based on interferometer working in the near-infrared (NIR) region where directional couplers were used in splitting and combining the input power to and from the two arms of the interferometer with 50/50 splitting ratio at 1550nm. Slot-waveguide is used in the sensing arm of the interferometer and strip-to-slot and slot-to-stip converters with high coupling efficiency were used for transforming the optical mode. Finite difference eigenmode (FDE) solver was used to calculate its mode field profiles, effective index, and loss to optimize the waveguide dimensions and to achieve a waveguide sensitivity of 0.7 at 1550nm for 220nm silicon thickness. Three-dimensional finite-dif-ference-time-domain (3D-FDTD) method was used in the analysis and optimization of the proposed gas sensor. Results show significant improvement in the figure-of-merit (FOM) and reduction of device area. The sensor also exhibits low insertion loss (IL) leading to a low detection limit. The proposed sensor is easily fabricated using CMOS technology which is essential for mass-scale fabrication, and thus a low-cost sensor can be integrated with optical fiber communication systems and optoelectronic systems. Therefore, the proposed sensor has the potential to be a key component in lab-on-a-chip (LOC) systems.
© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Mohamed M. El-Rayany, Raghi S. El Shamy, and Mohamed A. Swillam "A compact silicon-on-insulator gas sensor", Proc. SPIE 10923, Silicon Photonics XIV, 109231M (12 April 2019);

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