Silicon nitride based biosensor using array of coupled multi slot waveguide structure

Author's Department

Chemistry Department

Fifth Author's Department

Computer Science & Engineering Department

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https://doi.org/10.1088/2040-8986/ae074d

All Authors

Dana S. Akil Passant Hesham Hesham A. Attia Mulan E. Ahmed M. A. Swillam

Document Type

Research Article

Publication Title

Journal of Optics United Kingdom

Publication Date

9-1-2025

doi

10.1088/2040-8986/ae074d

Abstract

This paper investigates a study concerning the multi-mode multi-slot interference waveguide based on silicon nitride intended for optical biosensor applications for virus detection and compact optical sensing in both the visible and infrared regions. The proposed design consists of five parallel closed slot waveguides exited by launching the fundamental transverse electric mode through the central slot waveguide. The configuration enables strong coupling between the adjacent waveguides and enhances light-analyze interaction. An analytical expression for the self-imaging position is derived using both multimode interferometer (MMI) and coupled-mode theory, and the results are validated using commercial simulation software based on the finite-difference time-domain method. By tuning the geometry, we demonstrate enhanced optical confinement in the slot region, which improves the light-analyze interaction. The structure achieves a maximum sensitivity of 1722nm/RIU in one of the ports in the visible region and 1898nm/RIU in one of the ports in the infrared, with a compact device footprint of 170µm. Compared to previous slot or MMI-based sensors, our design has improved sensitivity, dual-band operation, and CMOS-compatible integration on the SiNOI platform, which makes it a promising candidate for label-free biochemical sensing applications.

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